A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

calculusxy

  • one year ago

If the speedometer of a car reads a constant 40km/hr, can you say the car has a constant velocity? Why or why not?

  • This Question is Closed
  1. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Michele_Laino This is like basic physics.

  2. alekos
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    velocity is defined as speed and direction

  3. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    I think that we can only say that the magnitude of our velocity is 40 Km/h

  4. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    namely, the motion of our car can be a uniform circular motion

  5. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So is it a yes?

  6. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    I think no, since as @alekos as well said the velocity is a vector quantity, which is defined by a speed or magnitude and a direction

  7. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So since it doesn't have a specific direction it cannot be considered as a "constant velocity," even though it has a constant speed?

  8. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes! That's right!

  9. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I have more questions, since I like to make sure many things. :)

  10. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    ok!

  11. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    What two controls in a car can use a change in speed?

  12. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I wrote the gas and brake pedals. But I am not sure if I should include the steering wheel, since it might change the velocity as well.

  13. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    I think that you have to include the steering wheel, since by means of the steering wheel we can bend the trajectory of our car, so we can change the velocity of our car

  14. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So do i write the two pedals (gas and brake) and the steering wheel?

  15. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes! I think so!

  16. sweetburger
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I agree that the steering wheel would cause a change in direction and therefore could have affect on the velocity

  17. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks for the continuous help. Next question: What quantity describes how quickly you change how fast you're traveling?

  18. sweetburger
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Acceleration? right?

  19. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes that's what I thought. But I am not quite sure.

  20. sweetburger
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    change in velocity over time*

  21. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    right! The steering wheel can produce a centripetal acceleration which is acting on our car @sweetburger

  22. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Michele_Laino For this question:What quantity describes how quickly you change how fast you're traveling? Would the answer be "acceleration"?

  23. alekos
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Previously you asked "What two controls in a car can change the speed?" (not velocity) that would only be brake and gas pedal.

  24. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes! I think so, since the acceleration, as a number, is the change in speed

  25. sweetburger
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @alekos I think you are correct considering it is only asking for change in speed.

  26. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    you are right! @alekos

  27. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    What is the acceleraiton of a car that travels in a straight line at a constant speed of 100km/hr?

  28. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the acceleration would be 100km/hr since it is travels in a straight line

  29. sweetburger
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    if it is at a constant speed of 100km/hr there is no change in velocity so 0/t = 0

  30. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    if the speed is constant, then the acceleration as a simple number, and not as a vector quantity, is zero

  31. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Oh okay

  32. sweetburger
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the velocity must change over a specific period of time to find a acceleration value

  33. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    the acceleration as a vector quantity, since the motion is along a straight line, is the null vector

  34. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    What is the acceleration of a car moving along a straight line path that increases its speed from zero to 100km/hr in 10 seconds?

  35. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes that's why i deleted it

  36. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    we have: 100 Km/h= 27.78 m/sec so acceleration is: 27.78/10=2.778 m/sec^2

  37. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yeah i was overlooking the "per hour" thank you for correcting that

  38. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    BY how much does the speed of a vehicle moving in a straight line change each second when it is accelerating at 2km/hr (two kilometers per hour per second; that is every second, the velocity is increasing two kilometers per hour.)

  39. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    after a time t (seconds), the requested change is 2*t Km/h

  40. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I don't quite understand

  41. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    by definition, acceleration a is given by the subsequent formula: \[a = \frac{{\Delta v}}{{\Delta t}}\] so we have: \[\Delta v = a\Delta t\]

  42. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    now, a= 2(Km/h)/sec and if \Delta t= 1 seconds, then we can write: \[\Delta v = a\Delta t = 2 \times 1 = 2\frac{{Km}}{h}\]

  43. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ansur at my fb : https://www.facebook.com/ParthKohli

  44. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    What does \[a \Delta t\] mean

  45. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Michele_Laino

  46. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Moving on to the next question: Why does the unit of time never twice in the unit of acceleration?

  47. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Would it be that the acceleration is found by dividing the velocity by time: \[(distance / time) / time => distance / time^2\]

  48. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    \[a\Delta t\] is the change in speed

  49. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So how would i calculate the speed?

  50. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    QUestion: Calculate the speed (in m/s) of a skateboarder who accelerates from rest for 3 seconds down a ramp at an acceleration of 5/m^2.

  51. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    here we have to apply this formula: \[v = a\Delta t = 5 \times 3 = ...m/\sec \]

  52. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so for this question would we do: \[V_f = V_i + (acceleration \times time)\]

  53. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes! nevertheless the initial speed is zero, since the skateboarder is starting from the rest

  54. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    V_i = 0 (initial velocity) acceleration = 5 m / s^2 time = 3 seconds \[V_f = 0 + (5 \times 3)\]

  55. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    that's right!

  56. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    15 m/s ?

  57. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes!

  58. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    THANK YOU SO MUCH!!! Last question: Which has more acceleration when moving in straight line: car increasing its speed rom 50-60km/hr or a bicycle that goes from 0 to km/hr in the same time? Why?

  59. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    bycicle goes from 0 to ?

  60. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    10km/hr Sorry

  61. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    if we consider a time interval \Delta t measured in hours, then the acceleration of the car is: \[{a_{CAR}} = \frac{{\left( {60 - 50} \right)}}{{\Delta t}} = \frac{{10}}{{\Delta t}}\;\frac{{Km}}{{{h^2}}}\] whereas the acceleration of the bycicle is: \[{a_{BYCICLE}} = \frac{{\left( {10 - 0} \right)}}{{\Delta t}} = \frac{{10}}{{\Delta t}}\;\frac{{Km}}{h}\]

  62. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    oops.. \[{a_{BYCICLE}} = \frac{{\left( {10 - 0} \right)}}{{\Delta t}} = \frac{{10}}{{\Delta t}}\;\frac{{Km}}{{{h^2}}}\]

  63. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So these are both the same right?

  64. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    sorry for my english: bicycle*

  65. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes! They are the same

  66. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks!!!!!! I honestly love your help, you have been with me for the past hour!! OMG no one, believe me does that much, except for you!

  67. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    :)

  68. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Sorry, but can you explain me the answer for the question: "BY how much does the speed of a vehicle moving in a straight line change each second when it is accelerating at 2km/hr (two kilometers per hour per second; that is every second, the velocity is increasing two kilometers per hour.) "

  69. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I still didn't get it :(

  70. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    the speed change as function of time interval \Delta t, is given by the subsequent formula: \[\Delta v = a\Delta t\] where a is the acceleration

  71. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    in our case, we have: \[a = 2\frac{{Km/h}}{{\sec }}\]

  72. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    so, if we consider a time interval \Delta t = 1 second, then after that time interval the speed change is: \[\Delta v = a\Delta t = 2 \times 1 = 2\frac{{Km}}{h}\] namely the requested speed change is: 2 Km/h

  73. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So the answer itself is 2km/hr ?

  74. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes!

  75. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you! And for the question with the speed from 0 ti 100km/hr in 10 seconds how did you get 27.78 m/sec

  76. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    since we have to divide by 3.6, namely 100/3.6 = 27.78 (approximated value)

  77. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    why 3.6?

  78. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    more explanation, we have: \[1\frac{{Km}}{h} = \frac{{1000}}{{3600}}\frac{m}{{\sec }} = \frac{1}{{3.6}}\frac{m}{{\sec }}\]

  79. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    therefore: \[1\frac{m}{{\sec }} = 3.6\frac{{Km}}{h}\]

  80. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Oh okay!

  81. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you soo.... much! May I know what times you are available in OS so that if i need help in physics/math, I can come and ask for your help?

  82. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    I'am available from 16:00 (Italy time zone)

  83. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Well I am in NY so what would be the time in EST?

  84. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    I think 16-6= 9:00 am

  85. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    sorry: 16-6= 10:00 am

  86. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh okay so it's like 8pm in italy now?

  87. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    yes! at the moment it is 19:57 from me

  88. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    you use the military time a lot?

  89. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    or the 24 hour standard clock?

  90. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    I use the standard 24 hour clock

  91. calculusxy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay b/c i use am and pm. anyway, thank you so much for your help. i REALLY appreciate it :)

  92. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    :)

  93. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.