Question

Susan and Hannah are each riding a swing. Susan has a mass of 25 kilograms, and Hannah has a mass of 30 kilograms. Susan’s swing moves with a velocity of 10 meters/second, while Hannah’s swing moves with a velocity of 8.5 meters/second. Susan’s kinetic energy is (1080,1250,1350, or 1500) joules. Susan’s kinetic energy is greater than Hannah’s because: Speed has a greater effect than mass, Mass has a greater effect than speed, Mass and Speed have the same effect, or Mass and Speed dont have any effect?

Answer 1

Answer:

Kinetic energy is given by:

K.E. = 0.5 m v²

Susan has mass, m = 25 kg

Velocity with which Susan moves is, v = 10 m/s

Hannah has mass, m' = 30 kg

Velocity with which Hannah moves is, v' = 8.5 m/s

Kinetic energy of Susan:

0.5 m v² = 0.5 × 25 kg × (10 m/s)² = 1250 J

Kinetic energy of Hannah:

0.5 m v'² = 0.5 × 30 kg × (8.5 m/s)² = 1083.75 J

Susan's kinetic energy is 1250 J and Hannah's kinetic energy is 1083.75 J.

Since kinetic energy is dependent on mass and square of speed. Thus, speed has a greater effect than mass. As it is evident from the above example. Susan has greater kinetic energy due to higher speed than Hannah.