The same formula of work can be applied to all the questions. The answers are:
E1. 100J
E2. 40N
E3. 5m
E4. a.) 360 J b.) 240 J c.) 120 J
El. If a horizontally directed force of 40 N is used to pull a box a distance of 2.5 m across a tabletop. The formula to get the much work that will be done by the 40 - N force will be
Work done = force x distance
Work done = 40 x 2.5
Work done = 100 J
E2. If a woman does 160 J of work to move a table 4 m across the floor. We will use the same formula to calculate the magnitude of the force that the woman applied to the table assuming the force is applied in the horizontal direction.
Work done = force x distance
160 = 4F
F = 160/4
Force F = 40 N
E3. Given that a force of 60 N used to push a chair across a room does 300 J of work. Same formula to get how far the chair move in this process.
Work done = force x distance
300 = 60 x distance
distance = 300/60
Distance = 5 m
Therefore, the chair moved 5m away.
E4. Given that a rope applies a horizontal force of 180 N to pull a crate a distance of 2 m across the floor. And a frictional force of 120 N opposes this motion.
a. The work done by the force applied by the rope can be found by
W = F x S
W = 180 x 2
W = 360 J
b. What is the work done by the frictional force?
W = 
x s
W = 120 x 2
W = 240 J
c. What is the total work done on the crate?
W = (F - ) x distance
Where = frictional force
Substitute all the parameters
W = (180 - 120) x 2
W = 60 x 2
W = 120 J
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