Question

Which statement best explains why running on a track with constant speed at 3m/s is not work but climbing a mountain at 1m/s is work?

1. At constant speed, change in the kinetic energy is zero but climbing a mountain produces change in the potential energy
2. At constant speed, change in the potential energy is zero, but climbing a mountain produces change in the kinetic energy.
3. At constant speed, change in the kinetic energy is finite, but climbing a mountain produces no change in the potential energy.
4. At constant speed, change in the potential energy is finite, but climbing a mountain produces no change in the kinetic energy.

Answer 1

1. At constant speed, change in the kinetic energy is zero but climbing a mountain produces change in the potential energy

Step-by-step explanation:

According to work-energy theorem, work done in moving an object from one point to another is equal to change in mechanical energy ( kinetic energy or potential energy ) of the object.

Kinetic energy is given by;

K.E = ¹/₂m(Δv)²

where;

Δv is change in speed

at constant speed, Δv = 0

Potential energy is given by;

P.E = mgΔh

where;

Δh is change in height,

there is change in height in climbing a mountain

Therefore, the best explanation in the given options is "1".

"At constant speed, change in the kinetic energy is zero but climbing a mountain produces change in the potential energy"