Work - Example 7.1-2

 

Consider a block being pushed along a frictionless surface from position x₁ to position x₂.

 

 

In your book, draw a free-body diagram of the block. Click on the figure to see the results.

 

What is the resultant force F that acts on the particle?

 

F = (N -mg) i + P j
F = P i + (N - mg) j
F = P + N - mg

 

 

 

What is the work done by F on the particle?

 

U_1-2 = P(x₂ - x₁)
U_1-2 = P(x₁ - x₂)
U_1-2 = (P + N - mg)(x₂ - x₁)

 

 

 

Which of the following statements are true?

Check all that apply.

 

The work done by a force F acting at an angle to the displacement Δx is equal to U = FΔx.
The work done by a force F pointing in the direction of the displacement Δx is equal to U = FΔx.
The work done by a force F that is perpendicular to the direction of the displacement Δx is equal to zero.
The work done by a force F pointing in the direction of the displacement Δx is negative.