1. A sailor pulls a boat along a dock using a rope at an angle of 60.0º with the horizontal. How much work does the sailor do if he exerts a force of 255 N on the rope and pulls the boat 3.00 m? W = FdcosO =255 x 3 x cos 60 =

2. An elephant pushes with 2000 N at an angle of 33o above the horizontal on a load of trees. It then pushes these trees for 150 m. How much work did the elephant do?

3. Hans Full is pulling on a rope to drag his backpack to school across the ice. He pulls upwards and rightwards with a force of 22.9 Newtons at an angle of 35o above the horizontal to drag his backpack a horizontal distance of 129 m. Determine the work done upon the backpack.

4. If 100 N force has 30o angle pulling on a 15 kg block for 5 m. What’s the work?

(1)Work done by snail is 382.5 N

(2)Work done by ELEPHANT is 25160 N

(3)Work done by HANS is 2420 N

(4)Work done on block is 433 N

Explanation:

The work done due to force F applied at an angle θ from the horizontal to the body is give by

Work done = Fscosθ where, s is distance traveled by body

Case 1: F= 255N , s= 3.00m and θ = 60.

Work done = Fscosθ = 255 x 3.00 x cos60. = 382.5N

thus work done by snail is 382.5 N

Case 2: F= 200N , s= 150m and θ = 33.

Work done = Fscosθ = 200 x 150 x cos33. = 25160N

thus work done by elephant is 25160 N

Case 3: F= 22.9N , s= 129m and θ = 35.

Work done = Fscosθ = 22.9 x 129 x cos35. = 2420N

thus work done by Hans is 2420 N

Case 4: F= 100N , s= 5m and θ = 30.

Work done = Fscosθ = 100 x 5.00 x cos30. = 433N

thus work done on block is 433 N

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