A box accidentally falls from the back of a truck and hits the ground with a speed of 15m/s. It slides along the ground for a distance of 45 m before coming to rest. Determine

Question

a) the length of time the box slides before stopping
c) the time it takes to slide the last 10 m.

Answer 1

a) Its average speed while coming to a stop is 7.5 m/s. Divide 45 m by that average speed to get the time required. You get 6.00 s

b)The speed while slowing down is
V = 15 [1 - (t/6)]

The time required to go 35 m is given by
Integral V dt = 35 = 15 t - (5/4)t^2
0 to t
Solve that quadratic for t. That will be the time required to slide the first 35 m. Subtract that from 6 s for the answer.

Answer 2

Why is the velocity 7.5?

Answer 3

A better solution is using the big 5 equations

Answer 4

the area under the velocity versus time graph gives you the total displacement so;
30.t/2 = 45
t= 30