Sam is pulling a box up to the second story of his apartment via a string. The box weighs 53.3 kg and starts from rest on the ground. Sam is pulling upwards with a force of 64 N. At the top, the box is pulled up to a height of 19.1 m. What is the total work performed for Sam to pull the box up to his height?

W = 1222.4 J = 1.22 KJ

Explanation:

The work done on an object is the product of the force applied on it and the displacement it covers as a result of this force. It must be noted that the component of displacement in the direction of force should only be used. Hence, the work can be calculated as:

W = F d Cosθ

where,

W = Work Done = ?

F = Force Applied = 64 N

d = Distance Covered by Box = 19.1 m

θ = Angle between force and displacement = 0°

Therefore,

W = (64 N)(19.1 m)Cos 0°

W = 1222.4 J = 1.22 KJ

b.

explanation:

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