Download Chapter 8 Practice Test Name 1. A 30 kg object is set into orbit 7.5 x

Chapter 8 Practice Test
Name ________________________________
1. A 30 kg object is set into orbit 7.5 x 1010 m away from the center of the Earth by a spaceship. The Earth’s mass is 5.98 x 10
24
kg .
a. What force of gravitational attraction does the object experience towards the Earth?
b. If, when the object was released, it just happened to be exactly the same distance from the sun (mass of the sun = 1.99 x 10
30
kg )as the Earth, would it feel more, less, or the same amount of gravitational attraction to the sun? Explain.
2. a. A 1000 kg object and a 2000 kg object are placed so that they experience a gravitational force of 3 N. How far apart are
the two objects?
b. What acceleration would the 2000 kg object experience because of the gravitational attraction if there were no resistance
forces
3. A six kg object is placed .08 meters away from a second object and experiences a .00054 N force of attraction towards the
second object. What is the mass of the second object?
4. a. What gravitational attractive force does Jupiter experience towards the Sun?
Mass of the Sun = 1.99 x 1030 kg
Mass of Jupiter = 1.9 x 1027 kg Distance between Sun / Jupiter = 778 x 109 m
b. Assuming a circular orbit, at what linear velocity does Jupiter orbit the Sun?
c. How many days does it take Jupiter to orbit the sun?
5. Communications satellites are designed to stay over one spot on the Earth (a geosynchronous orbit). In order to do this it is
required that they travel in a circular orbit with a constant linear velocity of 29,700 m/s. At what distance from the center of
the Earth do these satellites need to orbit to have that velocity provided only by the Earth’s Gravitational attraction? The mass
of the Earth is 5.98 x 1024 kg.
6. A 2130 kg car drives around a flat curve with a radius of 100 m without sliding or skidding. The coefficient of friction
between the road and tires is .6
A. What is the normal force of the car?
B. What is the friction force between the tires and the car
C. What is the centripetal force between the tires and car?
D. What is the maximum velocity the car could drive at without sliding?
E. At that speed, what is the centripetal acceleration of the car?
7. A .8 kg marble is swung on the end of a string in a flat horizontal circle of radius .6 m at a constant angular velocity of 6.3
rad/s.
A. Calculate the centripetal acceleration of the marble.
B. What force causes the centripetal acceleration?
C. Calculate the tension force in the string.
D. If the string will break when the tension force exceeds 400 N, find the maximum speed it can be swung at without breaking.
8. A roller coaster designer wants to put a vertical loop of radius 16. m in a ride. The maximum load of the rollercoaster cars
will be 2400 kg.
A. Draw a free body diagram of the car at the top of the loop.
B. What forces provide the centripetal force at this point?
C. What is the minimum velocity required for the rollercoaster in order for it to make it around the loop without the car or
people falling downward?
D. As a safety margin, the designer plans to make the rollercoaster go at twice the critical speed (twice as fast as you just
calculated). At that speed, calculate the centripetal force on the rollercoaster.
E. At that safer speed, calculate the normal force the track needs to provide at the highest point.
F. At that safer speed, calculate the normal force the track needs to provide at the lowest point.
9. A bicycle tire has a diameter of .56 m, and spins one full turn in .08 seconds.
a. What is the tires angular speed, ω, in rads/sec?
b. What is the linear velocity, v, of a point on the edge of the tire in m/s?
c. If it maintains a constant speed, find the angular displacement, in degrees, after 1 minute.
10. A pottery wheel has a radius of .3 m and is initially spinning at 55 rpm. The power is turned off and because of
friction the wheel slows down with an angular acceleration of 0.25 rad/s2.
a. Find the angular speed, in radians/second, of the wheel after 7 seconds?
b. How long will it take the wheel to come to a stop?
c. How many times will the wheel rotate after the power is turned off?
11. A spinning top spins at 82 rad/s gradually slows because of friction and topples after 30 seconds at an angular speed of 18
rad/s.
a. What was the angular acceleration of the top?
b. Find the angular displacement of the top while slowing in rad/s.
12. A boy and girl sit on a merry go round spinning at 0.20 rot/s. The boy sits 2.5 meters from the center and the girl sits 1.25
meters from the center.
a. Which child has the greater rotational speed, ω? Explain.
b. Which child has the greater linear speed, v? Explain.