Answer:
The acceleration is about 9.8 m/s2 (down) when the ball is falling.
Explanation:
The ball at maximum height has velocity zero
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
a = Acceleration due to gravity = 9.8 m/s² (positive downward and negative upward)

The accleration 9.8 m/s² will always be acting on the body in opposite direction when the body is going up and in the same direction when the body is going down. The acceleration on the body will never be zero
Energy is the capacity for doing work..
Kinetic energy - Moving car
Potential energy - flowing water up the hill
Answer:
The blade of sharpener is made up of iron. Iron is a magnetic material because of this pencil sharpener gets attracted by the poles of a magnet although the body is made up of plastic.
40 dB is 20 dB more power than 20 dB is. 20 dB more means 100 times as much.