A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 5 years ago
help pls..
an elevator car whose floor to ceiling distance is equal to 2.7 m , starts from rest and ascends with a constant acceleration of 1.2 ms^2 .Two seconds later , a bolt drops from the car's ceiling .The time taken by the bolt to hit the floor of the elevator is
a. 1 s
b. 0.7 s
anonymous
 5 years ago
help pls.. an elevator car whose floor to ceiling distance is equal to 2.7 m , starts from rest and ascends with a constant acceleration of 1.2 ms^2 .Two seconds later , a bolt drops from the car's ceiling .The time taken by the bolt to hit the floor of the elevator is a. 1 s b. 0.7 s

This Question is Closed

Owlfred
 5 years ago
Best ResponseYou've already chosen the best response.0Hoot! You just asked your first question! Hang tight while I find people to answer it for you. You can thank people who give you good answers by clicking the 'Good Answer' button on the right!

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0b, See it wrt a person standing inside the elevator, and u would get it.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0At the point at which the bolt is dropped, its speed is equal to the speed of the elevator. It begins to accelerate at 9.81 m/s downward, but the elevator is accelerating 1.2 m/s upward. The bolt's acceleration relative to the elevator is 9.81 m/s  1.2 m/s = 8.61 m/s. It must travel 2.7 m. \[\Delta X = (1/2) (a t ^{2})\]It follows that \[t = \sqrt{\Delta X 2 / (2A)}\]I think you can figure it out from there.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0@LunaEques Well done but please Check ur unit for acceleration it is m/s^2 and not m/s

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0At the time of drop, acceleration of bolt w.r.t. car is (10+ (1.2)) and ... and the displacement( final position initial position) is 2.7...since we are taking everthing with respect to the elevator... so the initial velocity of the bolt wrt elevator would be zero..please note that the quantities along the positive X and Y axis are taken to be + and those along the  X and Y axis are taken to be negative... so the Third equation of motion will give you: so the equation is 0  2.7= 0.5 X (11.2) X t X t... which gives you t= 0.69 seconds which is close enuf to the option b..

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Basically you need to decide whether you think the elevator being accelerated up towards the bolt will effectively increase or decrease the bolt's acceleration. The short answer is it will effectively increase, but you need to try and picture this intuitively for the future.
Ask your own question
Sign UpFind more explanations on OpenStudy
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
 Engagement 19 Mad Hatter
 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.