When we shake a mango tree, the mangoes fall. It is because when we shake the tree, the mangoes tend to be at rest due to inertia whereas the branches are in motion. That is why the mangoes fall from the branches.

Any three differences between acceleration and retardation are:

Solution:

Initial velocity of car (u) = 45 km/hr = 45 * 1000/3600 = 12.5 m/s

Time taken (t) = 3 s

Since the car stops finally, final velocity of car (v) = 0 m/s

Now,

Retardation (-a) = (u - v)/t

= (12.5 - 0)/3

= 4.17 m/s²

Hence, the magnitude of retardation of the car is 4.17 m/s².

Let the car move a distance 's' before coming into rest than from equations of motion, we have,

s = ut - 1/2 (a)t² [acceleration is negative due to retardation]

= (12.5)3 - 1/2 (4.17) (3)²

= 18.375 m

Hence, the car travelled...

Given

initial velocity ( u ) = 72 km/hr = 72 x 1000 / 3600

= 20 m/s

acceleration due to gravity (g) = 10 m/s²

also, final velocity(v) = 0 m/s

for maximum height,

v² = u² - 2gH

or, 0 = 20² - 2 x 20 H

thus, H = 400/ 40

maximum height (H) = 10 m

again , for time to return to initial position.

total displacement(s) = 0

so,

s= ut - 1/2 gt²

or, ut = gt²

thus, T = u/g

= 20/10

total time taken = 2 sec

The fan tends to continue its circular motion even after it is switched off due to the inertia of motion. The fan rotates with a decrease in speed (this is because of air friction) and stops after a few minutes.

Solution:

Initial velocity of stone (u) = 72 km/hr = 72 * 1000/3600 = 20 m/s

The stone is acted by constant downward acceleration equal to the acceleration due to gravity of earth, i.e, a = -g = - 10 m/s²

At maximum height, the velocity of the stone becomes 0 for a very short time so, final velocity of stone (v) = 0 m/s

To find: maximum height (H) = ?

Using equations of motion,

v² = u² + 2aH

or, 0² = (20)² + 2(-10)H

or, 0 = 400 - 20H

or, 20H = 400

or, H = 400/20

So, H = 20 m

Hence, the maximum height...

Velocity is the rate of change of displacement.

Mathematically, Velocity (V) = displacement / time

If car A travels 10 meters in 5 seconds in a straight line, it's velocity is 2 m/s.