The motor does 20 J of work on the block, it means that the total mechanical energy of the block has increased by 20 J. But the increase in total mechanical energy is equal to the sum of the increases in potential energy and kinetic energy:

So, if the gravitational potential energy has increased by 15 J, the kinetic energy has increased by
0.425
BECAUSE 1000g makes 1Kg
so 425g will make 0.425 option a
The magnitude of the average force exerted on the ball by the wall is calculated below.
The average force exerted by the ball on the wall is 3 N
Explanation:
Given:
mass of the ball (m)=0.10 kg
speed (v) =3.0 m/s
time taken(t) =0.01 seconds
To calculate:
Average force(F) exerted by ball on the wall
We know;
F=(m×v)÷t
F=(0.10×3.0)÷0.01
<u><em>F=3 N</em></u>
Therefore the average force exerted by the ball on the wall is 3 N
A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.