You are Here: Home >< Physics

# Physics question ( mechanics) A level watch

1. A lift ascends with a constant acceleration, a, then travels with a constant speed and is finally brought to rest under a constant retardation, a. If the total distance travelled is h and the total time taken is t, show that the time spent travelling at constant speed is
(t ²-4h/a)^1/2
2. if you draw a speed-time graph it will look like a trapezium. the gradient of the sloping sides is a ( or -a ). let the length of the top be c ( this is the time of constant velocity ). the amount of time before c begins will be ( t - c )/2

the height P can be found because P/{( t - c )/2} = the gradient = a

so P = 2a/ ( t -c )

the area of the trapezium is (c + t ) x P/2 = h...

you should be able to continue.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: October 23, 2017
Today on TSR

### Congratulations to Harry and Meghan!

But did you bother to watch?

### What do you actually do at University?

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE