Question

a car accelerates uniformly for 10seconds to attain a velocity of 20ms it continues with uniform velocity for another 20seconds and decelerates so that it stops in 20seconds

Answer 1

Answer: 700m

Step-by-step explanation:

I'm going to assume you wanted to find the displacement. We can solve this problem by separating it into different intervals of time. Let's start with the first 10 seconds.

First, let's find the acceleration for the first 10 seconds using the formula

final velocity = initial velocity + acceleration * time

The final velocity at the end of the 10 seconds is given in the problem, 20m/s.

20 = 0 + a(10)

a = 2 m/s^2

Now use the formula x = x0 + v0t + 1/2(a)t^2 to solve for the displacement.

x = 0 + 0 + (1/2)(2)(10^2) = 100m

Let's find the displacement for the next 20 seconds:

distance = velocity * time

x = 20 * 20 = 400m

Now let's find the displacement for the last 20 seconds. We have to find the deceleration for this time interval as well.

final velocity = initial velocity + acceleration * time

0 = 20 + a*20

a = -1 m/s^2

x = 0 + 20(20) + (1/2)(-1)(20^2) = 200

Finding the net displacement:

100 + 400 + 200 = 700m