Question 1

A car travels around a circular track of radius $$50\ \mathrm{m} at a $$constant speed of $$20\ \mathrm{m/s}. $$What is the magnitude of the car's centripetal acceleration?

Accepted Answer

$$8\ \mathrm{m/s^2$}$$

Question 2

Which of the following best describes the direction of the net force acting on an object in uniform circular motion?

Accepted Answer

It points towards the center of the circle.

Question 3

A 0.5 kg ball is attached to a string and swung in a horizontal circle of radius $$2\ \mathrm{m} at a $$speed of $$4\ \mathrm{m/s}. $$What is the tension in the string?

Accepted Answer

$$16\ \mathrm{N}$$

Question 4

A satellite orbits Earth in a circular orbit. Which of the following statements is true about the forces acting on the satellite?

Accepted Answer

The gravitational force provides the centripetal force required for circular motion.

Question 5

If the frequency of revolution of an object in circular motion is doubled, what happens to its speed, assuming the radius remains constant?

Accepted Answer

The speed doubles.

Question 6

A 1.8 m long tetherball rope swings in a horizontal circle. If the ball moves at $$3\ \mathrm{m/s}$$, what is the net force acting on the ball of mass $$0.4\ \mathrm{kg}$$?

Accepted Answer

$$2.0\ \mathrm{N}$$

Question 7

Which equation correctly relates the period $$T$$ and frequency $$f of an $$object in uniform circular motion?

Accepted Answer

$$T = \dfrac{1}{f}$$

Question 8

A planet orbits the Sun at a mean distance that is 1.5 times that of Earth's distance from the Sun. According to Kepler's third law, what is the ratio of the planet's orbital period to Earth's orbital period?

Accepted Answer

$$T = (1.5$$)^{3/2}$$ \approx 1.84$$

Question 9

Which of the following is NOT a correct statement about centripetal force?

Accepted Answer

Centripetal force is a real force that always points away from the center of the circle.

Question 10

A 2 kg object moves in a circle of radius $$0.5\ \mathrm{m} at a $$speed of $$6\ \mathrm{m/s}. $$What is the magnitude of the net force acting on the object?

Accepted Answer

$$36\ \mathrm{N}$$

Question 11

A satellite is in perpetual free fall around the Earth. What does this mean in terms of its motion?

Accepted Answer

It is constantly falling toward Earth but has enough tangential velocity to keep missing it.

Question 12

Which of the following best explains why astronauts in the International Space Station appear weightless?

Accepted Answer

They are in continuous free fall around the Earth.

Question 13

If the net force acting on an object in circular motion is suddenly removed, what path will the object follow?

Accepted Answer

A straight line tangent to the circle at the point of release.

Question 14

A 1 kg mass is attached to a string and whirled in a vertical circle of radius $$2\ \mathrm{m}. At $$the top of the circle, the speed is $$5\ \mathrm{m/s}. $$What is the minimum tension in the string at this point?

Accepted Answer

$$0\ \mathrm{N}$$

Question 15

Which of the following equations gives the magnitude of the centripetal force $$F_c$$ acting on an object of mass $$m$$ moving at speed $$v in a $$circle of radius $$r$$?

Accepted Answer

$$F_c = \dfrac{mv^2$}{r}$$

Question 16

A 1000 kg car rounds a curve of radius $$50\ \mathrm{m} at a $$speed of $$14\ \mathrm{m/s}. $$What is the required frictional force to keep the car from skidding?

Accepted Answer

$$3920\ \mathrm{N}$$

Question 17

According to Newton's third law, when a planet exerts a gravitational force on the Sun, what does the Sun do?

Accepted Answer

The Sun exerts an equal and opposite gravitational force on the planet.

Question 18

If the mass of a satellite in orbit is doubled, but its orbital radius and speed remain the same, what happens to the required centripetal force?

Accepted Answer

It doubles.

Question 19

Which of the following best describes the relationship between the period $$T of a $$planet's orbit and the semi-major axis $$a of $$its orbit, according to Kepler's third law?

Accepted Answer

$$T^2$$ \propto $$a^3$$

Circular Motion and Orbital Motion: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards