1. The centripetal force on a car rounding a curve on a level road is provided by
a) gravity b) friction c) the engine d) the car’s brakes e) normal force

2. On a “banked” turn, what is providing the centripetal force on a car?
friction and tension
friction and gravity
friction and normal force
friction only

3. The moon’s mass is only 1. 2% of the earth’s mass
The moon’s mass is only 1.2% of the earth’s mass. Relative to the gravitational force the earth exerts on the moon, the gravitational force the moon exerts on the earth is
a) smaller b) the same c) greater d) depends on whether the moon is made of cheese or not

4. The moon’s mass is only 1. 2% of the earth’s mass
The moon’s mass is only 1.2% of the earth’s mass. The gravitational acceleration the earth experiences compared to the gravitational acceleration the moon experiences is
smaller
b) the same
c) greater

5. A bucket on a water wheel with a radius of 2
A bucket on a water wheel with a radius of 2.5 m makes one complete revolution in 4.2 seconds. How fast is the bucket moving?
a)7.48 m/s
b)3.7 m/s
c)2.6 m/s
d)1.87 m/s
v = d/t
d = Circumference = 2πr
v = 2π(2.5)/4.2
v = 3.7 m/s

6. A 0.5 kg ball moves in a circle 40 cm in radius at a speed of 4.0 m/s. Its centripetal acceleration is
F = mv2/r
ma = mv2/r
a = v2/r
a = 42/.4
a = 40 m/s2
a) 10 m/s2
b) 20 m/s2
c) 30 m/s2
d) 40 m/s2

7. If the mass of Sputnik was doubled, by what factor would the force change if it was to remain in the same circular orbit?
two times greater
four times greater
half as much
one-fourth as much
no change

8. Two small masses that are 10 cm apart attract each other with a force of 10 N. When they are 5 cm apart, with what force will they attract each other? (G = 6.67  Nm2/kg2)
a) 5 N
b) 2.5 N
c) 20 N
d) 40 N

9. An object moves in a circular path
An object moves in a circular path. If the radius is doubled while keeping the speed the same, then the centripetal force must be:
a) two times more b) half as much c) four times more d) one-fourth as much e) the same

10. A planet of mass 3  1028 kg is in orbit around a star with mass 3  1030kg. The radius of the orbit is 1.5  1010m. The speed of the planet in orbit is
a) 6.03  1048 m/s b) 1.15  1012 m/s c) 1.15  104 m/s d) 1.16  105 m/s

11. The speed of the planet from the previous question is 1. 16  105 m/s
The speed of the planet from the previous question is 1.16  105 m/s. What is the period of the planet’s orbit?
a)8.12  105 s b)4.21  106 s c)3.23  103 s d)2.74  103 s

12. The radius of the path of an object in constant circular motion is doubled. The centripetal force needed if its speed remains the same is
a) half as great as it was before b) the same as before c) twice as great as before d) four times as great as before

13. Consider a roller coaster doing a loop
Consider a roller coaster doing a loop. What provides the centripetal force?
Friction
Normal force
Tension
Gravity

14. Consider a roller coaster at the top of a loop
Consider a roller coaster at the top of a loop. What provides the centripetal force?
Friction and Gravity
Normal force and Friction
Tension and Normal Force
Gravity and Normal Force
Centripetal Force and Gravity