4. A box of old textbooks is on the middle shelf in the bookroom 1.3 m from the floor. If the janitor relocates the box to the shelf that is 2.6 m from the floor, how much work does he do on the box. The box has a mass of 10.0 kg.

127.53 J

Explanation:

Given that

Height of the floor, h = 1.3 m

Acceleration due to gravity, g = 9.81 m/s²

Mass of the box, m = 10 kg

To find the work done on the box by the janitor, we use the formula for potential energy. Remember that potential energy is actually the energy stored in an object as a result of its position.

P.E = mgh, substituting each parameters for its value, we then have

P.E = 10 * 9.81 * 1.3

P.E = 127.53 J

Therefore, we can conclude that the amount of work done on the box by the janitor is 127.53 J

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

i don't understand. explain it clearly