Question

A car starts at rest and accelerates at a rate of 5m/s. Find its velocity after 15 sec​

Answer 1

Answer:

v = a•t

v = a•tv = 5 m/s^2 • 15 s = 75 m/s.

v = a•tv = 5 m/s^2 • 15 s = 75 m/s.The increase in velocity is 75 m/s.

Answer 2

Answer:

Explanation:

Avg speed × total times = total distance

20×25=500

Since acceleration in the 1st interval is same as deceleration in the 3rd interval and deceleration is from the same velocity achieved after acceleration, t 1=t3

s1=1/2 x 5t1^2

s2=(5t1)t2

s3=5t1 x t3- 1/2 x 5 x t1^2= 5t1 x t1- 1/2 x 5 x t1^2

s1+s2+s3=5t1t2+t1^2

5t1^2+5t1t2=500................equation 1

2t1+t2=25...................equation 2

solving 1and2 we get

t1=5,t2= 15s