kaylalynn Group Title Final exam review help?!?! 9 months ago 9 months ago

1. kaylalynn Group Title

I have 3 study sheets.

2. kaylalynn Group Title

3. kaylalynn Group Title

for # 1 i got 34km/h

4. Coolsector Group Title

no, you have to multiply by 3.6

5. kaylalynn Group Title

why?

6. Coolsector Group Title

|dw:1383926098747:dw|

7. kaylalynn Group Title

4.9 m change it to km it is 0.0049km/s * 60 *60 = 33.8

8. Coolsector Group Title

4.9 m change it to km it is 0.0049km this is correct. but then when you change seconds into hours you divide by 3600 since you divide it in the denominator it is like multiplying by 3600 so eventually 0.0049 * 3600 = 17.64 km/h

9. Coolsector Group Title

look at my draw

10. Coolsector Group Title

-> 0.0049km/s * 60 *60 = 33.8 it is 17.64 and not 33.8

11. Coolsector Group Title

0.0049 * 60 * 60 = 17.64

12. Coolsector Group Title

maybe you did mistake when you enter the numbers into the calculator

13. kaylalynn Group Title

the options are 94,000 km/h 34 km/h 2.6 km/h 34,000,000 km/h

14. Coolsector Group Title

well what can i say : http://www.unitconversion.org/velocity/meters-per-second-to-kilometers-per-hour-conversion.html you may check yourself here

15. Coolsector Group Title

0.0049 * 60 * 60 = 17.64 do it in the calculator and see

16. Coolsector Group Title

m is for meters right ? :O

17. kaylalynn Group Title

yes. Idk maybe the options are wrong. i keep getting 17.64 too.

18. Coolsector Group Title

i guess they are wrong

19. kaylalynn Group Title

A physical quantity X depends on mass, distance, and time. Use dimensional analysis to decide which of these is a possible expression for X where a is acceleration, v is velocity, and F is force. It's either X=Ft or X=1/2at^2 right?

20. Coolsector Group Title

well in x=1/2at^2 there is no mass

21. kaylalynn Group Title

would X=Ft work?

22. Coolsector Group Title

you have options ?

23. kaylalynn Group Title

yes X=Ft X=at X=vt and X=1/2at^2

24. Coolsector Group Title

yes Ft is the one

25. kaylalynn Group Title

for 3 I want to say B?

26. Coolsector Group Title

no

27. Coolsector Group Title

(just to make sure that you understand Ft units are [kg m / s] so it has mass distance and time)

28. Coolsector Group Title

now for 3. think what happens to y when x is small and when x is big..

29. kaylalynn Group Title

im confused

30. Coolsector Group Title

y = k/x for low values of x like when x goes to zero y will be very large for high values of x like when x goes to infinity y will be very low agree ?

31. kaylalynn Group Title

yes so thus my answer is A? AS X gets larger Y gets smaller.

32. Coolsector Group Title

yes ! A

33. kaylalynn Group Title

A balloon is expanded to the same volume as that of a human head. Do an order-of-magnitude estimate of the volume of this balloon in cm3

34. kaylalynn Group Title

1,000 cm3?

35. Coolsector Group Title

i think it iscorrect

36. kaylalynn Group Title

Which equation represents inverse proportionality? y=mx?

37. Coolsector Group Title

y=mx is linear proportionality direct ..

38. kaylalynn Group Title

y=mx y=mx^2 +b for nonzero b y=m/x y=mx^2

39. Coolsector Group Title

we had one like this before .. we want inverse so when one is high the other is low and when one is low the other is high ...

40. kaylalynn Group Title

so how would that be represented by an equation?

41. Coolsector Group Title

y=m/x as i said we had something like this before when we chose graph A

42. kaylalynn Group Title

oh. okay so its like the graph.

43. kaylalynn Group Title

A bicycle and rider travel along a road. Which of the following statements is true?

44. kaylalynn Group Title

The bicycle wheels rotate and translate the entire bike and the rider.

45. Coolsector Group Title

please write the other options as well

46. kaylalynn Group Title

Only the bicycle rider undergoes a translation. The bicycle wheels rotate and translate the entire bike and the rider. Only the bicycle undergoes a translation. Neither the bicycle nor the rider undergoes a translation.

47. Coolsector Group Title

48. kaylalynn Group Title

Suppose you are on a conveyor belt walkway at an airport. The walkway is moving at 0.50 m/s. You walk backward at 0.80 m/s to hand your suitcase to a friend who is 3.0 m behind you. A security guard stands alongside the walkway watching this. What is your speed relative to the guard? im not sure how to do this one.

49. Coolsector Group Title

so if you were not moving the relative speed was 0.5m/s correct?

50. kaylalynn Group Title

correct

51. Coolsector Group Title

now i guess the 0.8m/s walking backwards is relative to the belt! so we have: 0.5 - 0.8

52. Coolsector Group Title

do you understand why ?

53. kaylalynn Group Title

because he is walking backwards at 0.8

54. Coolsector Group Title

yes. not moving on the belt : 0.5 moving forward on the belt at x : 0.5 + x moving backward on the belt at x: 0.5 -x

55. kaylalynn Group Title

okay

56. kaylalynn Group Title

An airplane travels southwest a distance of 650 km at a velocity of 430 km/h. How long does the trip take in hours? 1.5?

57. Coolsector Group Title

correct

58. Coolsector Group Title

(650/430 = 1.5116...)

59. kaylalynn Group Title

On the position-time graph, what is the average velocity between 5 s and 10 s?

60. kaylalynn Group Title

61. kaylalynn Group Title

62. Coolsector Group Title

average velocity = (y2-y1) / (t2 -t1)

63. Coolsector Group Title

between two points : (t1,y1) and (t2,y2)

64. kaylalynn Group Title

4m/s?

65. Coolsector Group Title

at 5 sec the height is 10 so (5,10) and at 10 sec the height is 30 so (10,30) (30-10) / (10-5) = 4 correct

66. kaylalynn Group Title

A ball is dropped from a tower. It strikes the ground with a speed of +19.0 m/s. How high is the tower? 18.4m

67. Coolsector Group Title

you take the value of g as 9.8 ?

68. Coolsector Group Title

so yes correct..

69. Coolsector Group Title

v=gt so t=v/g now plug it into h = 0.5gt^2 = 0.5v^2/g = 18.4

70. kaylalynn Group Title

A ship travels south at 15 km/h for 4 h. What is the ship's displacement in km? 60km South?

71. Coolsector Group Title

correct 15*4 = 60

72. kaylalynn Group Title

A ball is rolling down a hill at +2.0 m/s. The ball is uniformly accelerating at +4.0 m/s2. What will the ball's velocity be 3.0 s later? 14m/s because v=u+at

73. kaylalynn Group Title

What additional force must be applied so that the block does not accelerate? 10N West?

74. kaylalynn Group Title

A 1,560 kg car is accelerating at 1.30 m/s2. What net force acts on the car? F=ma so 2028 rounds to 2030?

75. kaylalynn Group Title

Which statement is equivalent to Newton's first law? No net force acting on an object means no acceleration.

76. kaylalynn Group Title

A tension force of 2.50 N acts horizontally on a 2.00 kg block. The block accelerates at 0.750 m/s2. What is the force of kinetic friction? 1N?

77. kaylalynn Group Title

however the options are - 3.33 N - 1.50 N - 1.00 N - 4.00 N

78. Coolsector Group Title

ball - correct block - correct car - correct newtons first law - seems like it is correct but it is better to see the other options tension - it is -1 (remember that the kinetic friction force is against the direction of the motion) so you right about the magnitude but the sign is there to show what is the direction.

79. Coolsector Group Title

i guess that you solved it like 2.5 - Fk = ma and then you got Fk =1 but look at the equation - you already chose the direction with the minus sign.

80. kaylalynn Group Title

No net force acting on an object means no acceleration. For every action there is an equal and opposite reaction. Mass is directly proportional to weight. The acceleration of an object is the net force acting on it divided by its mass.

81. Coolsector Group Title

so it is right.

82. kaylalynn Group Title

The acceleration due to gravity on the surface of Mars is gmars = 3.7 m/s2. How much would an 11 kg bag of potatoes weigh on Mars? 41N?

83. Coolsector Group Title

yes

84. Coolsector Group Title

3.7*11

85. kaylalynn Group Title

The 48 kg student on skates pushes the 40 kg student on skates. The 40 kg student accelerates at 3.0 m/s2. What is the acceleration of the 48 kg student?

86. kaylalynn Group Title

87. Coolsector Group Title

newton's third law..

88. Coolsector Group Title

another hint ?

89. kaylalynn Group Title

F=ma?

90. Coolsector Group Title

newton's third says that if body A push body B with force F then body B push body A with the same force F in the opposite direction

91. kaylalynn Group Title

i feel stupid. sorry. ive been up all night

92. Coolsector Group Title

what is the force that acts on the 40kg student ?

93. Coolsector Group Title

94. kaylalynn Group Title

3m/s?

95. Coolsector Group Title

i asked about the force The 40 kg student accelerates at 3.0 m/s2 so the force on him is 40 * 3 = 120 N now according to newton's third law it is the force that acts on the second student as well (in the other direction) so 120 = 48 * a a = 120 / 48

96. kaylalynn Group Title

2.5 m/s

97. Coolsector Group Title

yes (well they might have there -2.5 since it is in the other direction)

98. kaylalynn Group Title

A 0.156 kg ice puck collides with a 0.170 kg ice puck. Both were originally moving at the same speed. Which one has the larger change in velocity?

99. kaylalynn Group Title

The 0.156 kg puck changes velocity the most. The 0.170 kg puck changes velocity the most. They both have the same change in velocity. They each have no change in velocity. I say it is the first one...

100. Coolsector Group Title

so the situation is that they are moving toward each other ? and then elastic collision ?

101. kaylalynn Group Title

i asume

102. Coolsector Group Title

correct then

103. kaylalynn Group Title

A diver jumps down on a springboard, bounces back up, and dives into the pool. Which of these is one of the action-reaction pairs involved?

104. kaylalynn Group Title

the force on the board as the diver bends it downward and the force on the diver as the board springs back up the force of the board on the diver as he moves down and the force of the board on the diver when pushed back up the springiness of the board in moving back up the force the diver exerts on the water and the force the water exerts on the diver

105. Coolsector Group Title

so what do you think ?

106. kaylalynn Group Title

A?

107. Coolsector Group Title

yes

108. Coolsector Group Title

newton's third law always involved two bodies

109. kaylalynn Group Title

A force of 100 N acts in a direction at an angle of 30° with the x-axis. What is the magnitude of the x component of the force?

110. kaylalynn Group Title

111. rajat97 Group Title

|dw:1383940674800:dw| yes the accurate answer is 86.5 newton

112. kaylalynn Group Title

Two movers are pushing a large crate along the ground, one with a force of 30 N east and the other with a force of 40 N north. The crate does not move. What is the magnitude of the force of static friction?

113. rajat97 Group Title

always remember for ease of resolving the forces into perpendicular directions, the component of force near the angle is the force x cos theta and the one which is away from it is f x sin theta

114. rajat97 Group Title

|dw:1383940923978:dw| the forces are perpendicular so the resultant is $\sqrt{F1^{2}+F2^{2}}$ therefore the resultant is 50N and the force of friction is equal to it

115. kaylalynn Group Title

Which of these is true about an object thrown straight up in the absence of air resistance?

116. kaylalynn Group Title

Its acceleration is constant. The direction of its velocity is constant. Its acceleration and velocity are both momentarily zero at maximum height. Its acceleration increases as it falls.

117. Coolsector Group Title

so what do you think ?

118. kaylalynn Group Title

C?

119. Coolsector Group Title

well no does g change during the motion ?

120. kaylalynn Group Title

i want to say no

121. Coolsector Group Title

because the acceleration does not change

122. kaylalynn Group Title

so it would be A?

123. Coolsector Group Title

yes

124. Coolsector Group Title

note that at the maximum height the velocity is indeed zero. but what makes it go down ? the acceleration.

125. kaylalynn Group Title

The velocity of an object increases from 5.0 m/s to 15 m/s in 2.0 s. What is the average acceleration of the object?

126. ayhan Group Title

5m/sn2

127. ayhan Group Title

ok

128. rajat97 Group Title

i'm on it average velocity is change in velocity in unit time so here it is 15-5/2 =5m/s^2

129. kaylalynn Group Title

is it + or -?

130. rajat97 Group Title

change in velocity is final velocity -initial vel as final vel is greater than initial vel , it will be posotive

131. rajat97 Group Title

and if vel is increasing, then acceleration is +ve

132. kaylalynn Group Title

What shape does a position vs. time graph have for an object in uniform acceleration?

133. kaylalynn Group Title

134. rajat97 Group Title

i think its cubic as the degree of the equation increases as we move towards position time graph i mean to say its linear in v-t graph so it may be quadratic in x-t graph

135. ayhan Group Title

hi again

136. kaylalynn Group Title

okay and hi

137. rajat97 Group Title

138. ayhan Group Title

ok.bye

139. rajat97 Group Title

140. rajat97 Group Title

somethings gotta go wrong with openstudy well i live in india and its 2:45 am and i think i shall sleep now but if you have any questions please post them i'm onine for 15 mins

141. kaylalynn Group Title

no, my mom needed help with something.

142. kaylalynn Group Title

A book is being pushed along a table at constant speed. The coefficient of static friction is 0.75, and the coefficient of kinetic friction is 0.30. The book has a mass of 0.50 kg. What is the force of friction?

143. kaylalynn Group Title

1.5N

144. Coolsector Group Title

correct