Question

1. A racing car moving with constant acceleration covers two successive kilometres in 30 seconds and 50 seconds respectively. find the acceleration of the car.

2. A ball is thrown vertically upwards with a velocity of 20 metre per second from the top of a multi-storey building the height of the point from where the ball is from 25 m from the ground.​

Answer 1

The acceleration of the car is calculated as 10 m/s.

What is acceleration?

The acceleration is the rate of change of velocity with time. Given that;

s = ut + 1/2 at^2

Assuming that the motion started from rest, u = 0 m/s

s = 1/2 at^2

2000 = 0.5 * a * (20)^2

a = 2000/ 0.5 *  (20)^2

a = 10 m/s^2

2) The time taken to reach the maximum height is gotten from;

v=u+at

0=20+(−10)t

t=2s

Then time taken to reach the maximum height;

s = ut + 1/2 at^2

s = 20(2)+0.5(−10)(2)^2

s = 20m

The maximum height is therefore 45 m thus;

45=0+0.5(10)(t)^2

t = 3s

Total time= 3+2= 5s

Learn more about acceleration:https://brainly.com/question/12550364?

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Answer 2

1. Initial velocity = u

acceleration = a

1000 = u(30) + 0.5a(30)²

1000 = 30u + 450a

velocity after covering 1 km = u + 30a

1000= (u+30a) (20) + 0.5a (20)²

1000= 20u + 800a

u = 35a

putting the value of u in above equation

so, a = 2/3

2. refer to the above attachment