Question 1

Which one of the following free-body diagrams best represents the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with unchanging velocity? $$F_f is $$the force of the floor on the person and $$F_g is $$the force of gravity on the person.

Accepted Answer

A diagram with $$F_f$$ upward and $$F_g$$ downward, with $$F_f = F_g.$$

Question 2

Future space stations will create an artificial gravity by rotating. Consider a cylindrical space station 300 m in diameter rotating about its central axis. Astronauts walk on the inside surface of the space station. What rotation speed will provide 'normal' gravity?

Accepted Answer

$$3.6 \ 	ext{rad/s}$$

Question 3

A box slides down a frictionless plane inclined at an angle $$	heta$$ above the horizontal. The gravitational force on the box is divided:

Accepted Answer

D) Parallel to the plane in the same direction as the movement of the box and perpendicular to the plane.

Question 4

A mass $$M is $$suspended by a rope over a pulley. What is the tension in the rope if the system is at rest?

Accepted Answer

$$T = Mg$$

Question 5

Engineers are designing a curved section of a highway. If the radius of curvature of the curve is $$194 \ 	ext{m}$$, at what angle should the curve be banked so that a car traveling at $$29.0 \ 	ext{m/s}$$ will stay on the road without the aid of frictional forces?

Accepted Answer

$$26.1^\circ$$

Question 6

A new roller coaster contains a loop-the-loop in which the car and rider are completely upside down. If the radius of the loop is $$13.2 \ 	ext{m}$$, with what minimum speed must the car traverse the loop so that the rider does not fall out while upside down at the top? Assume the rider is not strapped to the car.

Accepted Answer

$$12.5 \ 	ext{m/s}$$

Question 7

Two blocks are connected as shown to the right. The magnitude of the pull exerted by the connecting cord on body $$P$$ will be:

Accepted Answer

D) Less than $$F$$ but not zero.

Question 8

A car travels at steady $$40.0 \ 	ext{m/s}$$ around a horizontal curve of radius $$200 \ 	ext{m}. $$What is the minimum coefficient of static friction between the road and the car's tires that will allow the car to travel at this speed without sliding?

Accepted Answer

$$0.92$$

Question 9

The figure shows a $$100 \ 	ext{kg}$$ block being released from rest from a height of $$1.0 \ 	ext{m}. It $$then takes $$0.50 \ 	ext{s} to $$reach the floor. What is the mass of the other block? The pulley has no appreciable mass or friction.

Accepted Answer

$$54 \ 	ext{kg}$$

Question 10

A $$250 \ 	ext{kg}$$ crate is on a rough ramp inclined at $$30^\circ$$ above the horizontal. The coefficient of kinetic friction between the crate and ramp is $$0.2. A $$horizontal force of $$500 \ 	ext{N} is $$applied to the crate, pushing it up the ramp. What is the acceleration of the crate?

Accepted Answer

$$3.4 \ 	ext{m/s}^2$$

Question 11

A $$6.0 \ 	ext{kg}$$ box slides down an inclined plane that makes an angle of $$39^\circ$$ with the horizontal. If the coefficient of kinetic friction is $$0.2$$, at what rate does the box accelerate down the slope?

Accepted Answer

$$3.52 \ 	ext{m/s}^2$$

Question 12

The magnitude of the drag force of air resistance on a certain $$20.0-kg $$object is proportional to its speed. If the object has a terminal speed $$80.0 \ 	ext{m/s}$$, what is the magnitude of the drag force on the object when it is falling with a speed $$50.0 \ 	ext{m/s}$$?

Accepted Answer

$$150 \ 	ext{N}$$

Question 13

A car enters a $$300-m $$radius horizontal curve on a rainy day when the coefficient of static friction between its tires and the road is $$0.20. $$What is the maximum speed at which the car can travel around this curve without sliding?

Accepted Answer

$$24.8 \ 	ext{m/s}$$

Fundamental Concepts in Newtonian Mechanics: Forces, Motion, and Applications

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