Question 1

A box weighing 200 N is suspended from a vertical rope and remains at rest. What is the tension in the rope?

Accepted Answer

$$T = 200\ \mathrm{N}$$

Question 2

Which of the following statements best describes static equilibrium?

Accepted Answer

An object is at rest and the net force acting on it is zero.

Question 3

A skier is being towed up a hill at constant speed. Which statement is true about the forces acting on the skier?

Accepted Answer

The net force is zero.

Question 4

An elevator is moving upward and speeding up. Which of the following is true about the tension in the cable compared to the elevator's weight?

Accepted Answer

Tension is greater than the weight.

Question 5

Which equation must be satisfied for an object to be in equilibrium in the $$xy$$ plane?

Accepted Answer

$$\sum F_x = ma_x = 0$$ and $$\sum F_y = ma_y = 0$$

Question 6

A car of mass $$1500\ \mathrm{kg} is $$being towed at a steady speed by a rope that makes a $$20^\circ$$ angle with the horizontal. The friction force opposing the car's motion is $$320\ \mathrm{N}. $$What is the horizontal component of the tension in the rope?

Accepted Answer

$$T_x = 320\ \mathrm{N}$$

Question 7

Which of the following is NOT a correct step in constructing a free-body diagram?

Accepted Answer

Include velocity vectors for all moving objects.

Question 8

A rod lies on a frictionless sheet of ice, with one end tied to a wall by a rope. Which force does NOT act on the rod?

Accepted Answer

Friction force from the ice

Question 9

A $$500\ \mathrm{N}$$ orangutan hangs motionless from a vertical rope. What is the net force acting on the orangutan?

Accepted Answer

$$0\ \mathrm{N}$$

Question 10

A car is being towed at constant speed on a horizontal road. The tension in the rope is $$T$$, and the friction force is $$f. $$Which equation correctly relates $$T$$ and $$f$$?

Accepted Answer

$$T = f$$

Question 11

Which scenario describes dynamic equilibrium?

Accepted Answer

A car moving in a straight line at constant speed.

Question 12

In a free-body diagram for an object on an incline, how should the axes be oriented?

Accepted Answer

Parallel and perpendicular to the incline.

Question 13

A $$1500\ \mathrm{kg}$$ car is towed at constant speed by a rope at $$20^\circ$$ above the horizontal. The friction force is $$320\ \mathrm{N}. $$What is the magnitude of the tension in the rope?

Accepted Answer

$$T = \dfrac{320}{\cos 20^\circ}$$

Question 14

If the sum of the forces in the $$x$$ and $$y$$ directions are both zero, what can be said about the object's acceleration?

Accepted Answer

The object has zero acceleration.

Question 15

A skier is being towed up a hill at constant speed. Which force balances the friction force?

Accepted Answer

The tension in the rope.

Question 16

Which of the following is a correct application of Newton's second law for equilibrium?

Accepted Answer

$$\sum F = ma = 0$$

Question 17

A block is at rest on a frictionless surface. Which statement is true?

Accepted Answer

The net force on the block is zero.

Question 18

When drawing a free-body diagram, what does the length of each force vector represent?

Accepted Answer

The magnitude of the force.

Question 19

A $$500\ \mathrm{N}$$ orangutan hangs from a rope. If the rope is replaced with one that can only hold $$400\ \mathrm{N}$$, what will happen?

Accepted Answer

The rope will break.

Equilibrium and Free-Body Diagrams in College Physics

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