Question 1

If a highway curve is properly banked and posted at 45 mph,it is a good idea to drive somewhat below this speed if your tires are bald or if the road is icy.

Accepted Answer

A) True 
 B)False  False

Question 2

If there is no such thing as a centrifugal force,why does someone in a car making a turn feel as if he or she is being pulled toward the outside of the curve?

Accepted Answer

The car is making a turn,but the person in the car is not part of the car.According to Newton's First Law,you will move in a straight line until acted on by an outside force - thus,you move in a straight line while the car turns (at least until you run into the door.At this time,the car exerts a force on you,causing your direction of motion to change. ).

Question 3

A satellite is in orbit around a planet.The orbital radius is 34.0 km and the gravitational acceleration at that height is 2.3 m/s2.What is the satellite's orbital speed?

Accepted Answer

A) 280 m/s 
B) 8.8 m/s 
C) 28 m/s 
D) 88 m/s 
A) 280 m/s 
B) 8.8 m/s 
C) 28 m/s 
D) 88 m/s A

Question 4

A person ties a rock to a string and whirls it around in a vertical circle such that sometimes the rock is going straight upward and sometimes the rock is going straight down.She whirls the rock at the minimum speed (constant in time)such that the string is always taut (no sag).When is the tension the highest?

Accepted Answer

A) It is highest when the rock is at the lowest elevation. 
B) It is highest when the rock is at the highest elevation. 
C) The tension is constant as the rock moves around in a circle. 
A) It is highest when the rock is at the lowest elevation. 
B) It is highest when the rock is at the highest elevation. 
C) The tension is constant as the rock moves around in a circle.

Question 5

A tetherball is on a 2.1 m string that makes an angle of 44° with the vertical as it moves around the pole in a horizontal plane.If the mass of the ball is 1.3 kg,what is the ball's speed?

Accepted Answer

A) 3.7 m/s 
B) 2.9 m/s 
C) 3.4 m/s 
D) 4.2 m/s 
A) 3.7 m/s 
B) 2.9 m/s 
C) 3.4 m/s 
D) 4.2 m/s

Question 6

For astronauts in space,there is no atmosphere to slow their orbit.Why don't they just fly away to the moon?

Accepted Answer

The astronauts were initially placed the

Question 7

An electrical motor spins at a constant 2857.0 rpm.If the armature radius is 2.685 cm,what is the acceleration of the edge of the rotor?

Accepted Answer

A) 2403 m/s2 
B) 844.4 m/s2 
C) 241,100 m/s2 
D) 84.40 m/s2 
A) 2403 m/s2 
B) 844.4 m/s2 
C) 241,100 m/s2 
D) 84.40 m/s2

Question 8

Earth's gravity is caused by our planet's spin on its axis.

Accepted Answer

A) True 
 B)False

Question 9

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 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

A) 11.4 m/s 
B) 12.5 m/s 
C) 10.1 m/s 
D) 14.9 m/s 
A) 11.4 m/s 
B) 12.5 m/s 
C) 10.1 m/s 
D) 14.9 m/s

Question 10

If the mass of Earth and all objects on it were suddenly doubled,the acceleration due to gravity at the surface would become 4 times what it is now.

Accepted Answer

A) True 
 B)False

Question 11

A mass on a string is swung in a vertical circle at a constant speed.The string will break if the tension in the string exceeds a critical value.At what part of the circle is the string most likely to break,and why?

Accepted Answer

The string is most likely to break at th

Question 12

How is it possible for someone to remain in her seat (without any straps)while upside down on a loop-the-loop roller coaster?

Accepted Answer

If the velocity of the roller coaster ca

Question 13

-A ball of mass 8.0 kg is suspended by two wires from a horizontal arm,which is attached to a vertical shaft,as shown in the figure.The shaft is in uniform rotation about its axis such that the linear speed of the ball equals 2.3 m/s.The tension in wire 1 is closest to:

Accepted Answer

A) 39 N 
B) 49 N 
C) 29 N 
D) 20 N 
E) 9.8 N 
A) 39 N 
B) 49 N 
C) 29 N 
D) 20 N 
E) 9.8 N

Question 14

If I set the car cruise control at a certain speed and take a turn,the speed will remain the same.So,why am I accelerating?

Accepted Answer

If you observe a car actually performing

Question 15

A 23 kg mass is connected to a nail on a frictionless table by a (massless)string of length 1.3 m.If the tension in the string is 51 N while the mass moves in a uniform circle on the table,how long does it take for the mass to make one complete revolution?

Accepted Answer

A) 4.8 s 
B) 3.8 s 
C) 4.5 s 
D) 5.2 s 
A) 4.8 s 
B) 3.8 s 
C) 4.5 s 
D) 5.2 s

Question 16

From what height off the surface of Earth should an object be dropped to initially experience an acceleration of 0.5400 g?

Accepted Answer

A) 2298 km 
B) 1689 km 
C) 5426 km 
D) 2930 km 
A) 2298 km 
B) 1689 km 
C) 5426 km 
D) 2930 km

Question 17

If you stood on a planet having a mass four times higher than Earth's mass,and a radius two times longer than Earth's radius,you would weigh

Accepted Answer

A) the same as you do on Earth. 
B) two times more than you do on Earth. 
C) two times less than you do on Earth. 
D) four times more than you do on Earth. 
A) the same as you do on Earth. 
B) two times more than you do on Earth. 
C) two times less than you do on Earth. 
D) four times more than you do on Earth.

Question 18

Calculate the angular speed,in rad/s of a flywheel turning at 520.0 rpm.

Accepted Answer

A) 54.44 rad/s 
B) 8.656 rad/s 
C) 40.83 rad/s 
D) 60.97 rad/s 
A) 54.44 rad/s 
B) 8.656 rad/s 
C) 40.83 rad/s 
D) 60.97 rad/s

Question 19

While a Ferris wheel turns at uniform angular speed,a seat at the rim of the wheel has a nonzero radial acceleration toward the center of the wheel but a tangential acceleration of zero.

Accepted Answer

A) True 
 B)False

Question 20

What is the gravitational force acting on a person due to another person standing 2 meters away? Assume each individual has 59 kg mass.

Accepted Answer

A) 5.8 × 10-8 N 
B) 8.5 × 103 N 
C) 1.2 × 10-7 N 
D) 9.8 × 10-10 N 
E) 2.0 × 10-9 N 
A) 5.8 × 10-8 N 
B) 8.5 × 103 N 
C) 1.2 × 10-7 N 
D) 9.8 × 10-10 N 
E) 2.0 × 10-9 N

Exam 6: Circular Motion,orbits,and Gravity

If a highway curve is properly banked and posted at 45 mph,it is a good idea to drive somewhat below this speed if your tires are bald or if the road is icy.

If there is no such thing as a centrifugal force,why does someone in a car making a turn feel as if he or she is being pulled toward the outside of the curve?

A satellite is in orbit around a planet.The orbital radius is 34.0 km and the gravitational acceleration at that height is 2.3 m/s2.What is the satellite's orbital speed?

A tetherball is on a 2.1 m string that makes an angle of 44° with the vertical as it moves around the pole in a horizontal plane.If the mass of the ball is 1.3 kg,what is the ball's speed?

For astronauts in space,there is no atmosphere to slow their orbit.Why don't they just fly away to the moon?

An electrical motor spins at a constant 2857.0 rpm.If the armature radius is 2.685 cm,what is the acceleration of the edge of the rotor?

Earth's gravity is caused by our planet's spin on its axis.

If the mass of Earth and all objects on it were suddenly doubled,the acceleration due to gravity at the surface would become 4 times what it is now.

A mass on a string is swung in a vertical circle at a constant speed.The string will break if the tension in the string exceeds a critical value.At what part of the circle is the string most likely to break,and why?

How is it possible for someone to remain in her seat (without any straps)while upside down on a loop-the-loop roller coaster?

-A ball of mass 8.0 kg is suspended by two wires from a horizontal arm,which is attached to a vertical shaft,as shown in the figure.The shaft is in uniform rotation about its axis such that the linear speed of the ball equals 2.3 m/s.The tension in wire 1 is closest to:

If I set the car cruise control at a certain speed and take a turn,the speed will remain the same.So,why am I accelerating?

A 23 kg mass is connected to a nail on a frictionless table by a (massless)string of length 1.3 m.If the tension in the string is 51 N while the mass moves in a uniform circle on the table,how long does it take for the mass to make one complete revolution?

From what height off the surface of Earth should an object be dropped to initially experience an acceleration of 0.5400 g?

If you stood on a planet having a mass four times higher than Earth's mass,and a radius two times longer than Earth's radius,you would weigh

Calculate the angular speed,in rad/s of a flywheel turning at 520.0 rpm.

While a Ferris wheel turns at uniform angular speed,a seat at the rim of the wheel has a nonzero radial acceleration toward the center of the wheel but a tangential acceleration of zero.

What is the gravitational force acting on a person due to another person standing 2 meters away? Assume each individual has 59 kg mass.

Representing Motion

Motion in One Dimension

Vectors and Motion in Two Dimensions

Forces and Newtons Laws of Motion

Applying Newtons Laws

Rotational Motion

Equilibrium and Elasticity

Momentum

Energy and Work

Using Energy

Thermal Properties of Matter

Fluids

Oscillations

Traveling Waves and Sound

Superposition and Standing Waves

Wave Optics

Ray Optics

Optical Instruments

Electric Fields and Forces

Electric Potential

Current and Resistance

Circuits

Magnetic Fields and Forces

Electromagnetic Induction and Electromagnetic Waves

Ac Electricity

Relativity

Quantum Physics

Atoms and Molecules

Nuclear Physics

Filters

A satellite is in orbit around a planet.The orbital radius is 34.0 km and the gravitational acceleration at that height is 2.3 m/s².What is the satellite's orbital speed?