PhysicsLAB: Work and Energy Practice: Forces at Angles

In these exercises, you may use g = 10 m/sec².

Refer to the following information for the next four questions.

A force of 50 N, applied at an angle of 37º to the horizontal, is required to drag a block across the table at a constant velocity of 0.7 m/sec.

If the coefficient of friction between the block and the table is 0.20, what is the mass of the block?

40 kg23 kg20 kg17 kg

If the block is pulled for a total of 3 seconds, how much work was done by the applied force, F?

True or False. The amount of work done by friction on the block, during these three seconds, exactly equals the magnitude of the work done by the applied force, F.

TrueFalse

How much power was expended by the applied force, F, as it pulled the block across the table?

For each diagram, state the numerical value that should be substituted in for θ when using the work equation W = Fs cos θ.

Refer to the following information for the next question.

A block is being pushed across a frictionless surface by a force at 30º.

What is θ when calculating the work done by F?

Refer to the following information for the next question.

A block is sliding across a horizontal surface which is not frictionless.

What is θ when calculating the work done by F?

Refer to the following information for the next question.

A book is being held at a constant height and moved at a constant speed across a room.

What is θ when calculating the work done by the person carrying the book?

A ball is being whirled in a conical pendulum at the end of a 1-m string at a constant frequency.

What is θ when calculating the work done by the tension in the string?

Refer to the following information for the next question.

A block is being dragged up a 20º incline by a rope that acts at an angle of 15º to the incline's surface.

What is θ when calculating the work done by the tension in the rope?