Circular Motion and Gravitation Practice Questions
IB (International Baccalaureate) · IB Physics HL · 149 free MCQs with instant results and detailed explanations.
149
Total
50
Easy
72
Medium
27
Hard
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Sample Questions from Circular Motion and Gravitation
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Q1
Easy
What is the centripetal acceleration of an object moving in a circle of radius 5 m with a speed of 10 m/s?
A.
20 m/s²
B.
10 m/s²
C.
5 m/s²
D.
2 m/s²
Show Answer & Explanation
Correct Answer: A
Centripetal acceleration can be calculated using the formula a_c = v² / r. Here, v = 10 m/s and r = 5 m. Thus, a_c = (10)² / 5 = 100 / 5 = 20 m/s².
Q2
Easy
A satellite is in a stable orbit around the Earth at an altitude where gravitational force is acting on it. Which of the following statements is true about the satellite?
A.
It is accelerating towards Earth.
B.
It is not experiencing any forces.
C.
It moves at constant speed and constant velocity.
D.
It experiences a net force that acts away from Earth.
Show Answer & Explanation
Correct Answer: A
Even in a stable orbit, the satellite is subject to gravitational force, which causes it to accelerate towards the Earth. This acceleration is what allows it to maintain its circular path.
Q3
Easy
Which of the following factors does NOT affect the gravitational force between two objects?
A.
Mass of the first object
B.
Distance between the objects
C.
Speed of the objects
D.
Mass of the second object
Show Answer & Explanation
Correct Answer: C
The gravitational force between two objects is determined by their masses and the distance separating them, according to Newton's law of universal gravitation. The speed of the objects does not influence this force.
Q4
Medium
A car is moving in a circular track of radius 250 m at a constant speed of 20 m/s. What is the magnitude of the centripetal acceleration of the car?
A.
1.6 m/s²
B.
8.0 m/s²
C.
4.0 m/s²
D.
16.0 m/s²
Show Answer & Explanation
Correct Answer: B
Centripetal acceleration (a_c) is given by the formula a_c = v²/r. Here, a_c = (20 m/s)² / (250 m) = 8.0 m/s².
Q5
Medium
When an object is in uniform circular motion, which of the following statements about the net force acting on the object is TRUE?
A.
The net force is zero.
B.
The net force acts in the direction of motion.
C.
The net force acts towards the center of the circular path.
D.
The net force is always equal to the weight of the object.
Show Answer & Explanation
Correct Answer: C
In uniform circular motion, the net force is directed towards the center of the circular path, providing the necessary centripetal force.
Q6
Medium
A planet orbits a star in an elliptical orbit. Which of the following statements is true according to Kepler's laws?
A.
The planet moves fastest when it is farthest from the star.
B.
The line joining the planet and the star sweeps out equal areas in equal times.
C.
The orbit is always circular.
D.
The period of the orbit is independent of the semi-major axis length.
Show Answer & Explanation
Correct Answer: B
According to Kepler's second law, a line segment joining a planet and the star sweeps out equal areas during equal intervals of time, meaning the planet's speed changes.
Q7
Medium
A stone is tied to a string and swung in a vertical circle of radius 1.5 m. At the highest point of the swing, if the tension in the string is 5 N and the mass of the stone is 2 kg, what is the speed of the stone at this point?
A.
2 m/s
B.
3 m/s
C.
4 m/s
D.
5 m/s
Show Answer & Explanation
Correct Answer: B
At the highest point, the centripetal force is provided by the tension and weight of the stone. F_c = T + mg, where mg = 2 kg * 9.8 m/s² = 19.6 N. Then, mv²/r = T + mg, solving gives v = 3 m/s.
Q8
Hard
A mass m is attached to a string and whirled in a horizontal circle with radius r at a constant speed v. If the tension in the string is T, which of the following equations correctly relates T, m, v, and r?
A.
T = m(v^2)/r
B.
T = mv^2 + mg
C.
T = mg - mv^2/r
D.
T = mv^2/r
Show Answer & Explanation
Correct Answer: D
When an object moves in a circular path, the only force providing the centripetal acceleration is the tension in the string. The relation is T = mv^2/r, where T is the tension, m is the mass, v is the speed, and r is the radius of the circle.
Q9
Hard
A satellite is in a circular orbit at a height of 300 km above the Earth's surface. If the radius of the Earth is approximately 6400 km, what is the orbital speed of the satellite? (Take g = 9.81 m/s²)
A.
7.67 km/s
B.
8.00 km/s
C.
6.28 km/s
D.
5.45 km/s
Show Answer & Explanation
Correct Answer: A
The orbital speed can be calculated using the formula v = √(g * r), where r is the total radius from the center of the Earth. Here, r = 6400 km + 300 km = 6700 km = 6.7 × 10^6 m. Hence, v = √(9.81 * 6.7 × 10^6) = 7.67 km/s.
Q10
Hard
A satellite is in a circular orbit around a planet. If the radius of the satellite's orbit is doubled, what happens to the gravitational force acting on it?
A.
The gravitational force is doubled.
B.
The gravitational force remains the same.
C.
The gravitational force is halved.
D.
The gravitational force is decreased to a quarter.
Show Answer & Explanation
Correct Answer: D
The gravitational force is inversely proportional to the square of the distance from the center of the planet. If the radius is doubled, the distance increases by a factor of 2, resulting in the force being decreased by a factor of 2^2, or 4.
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Circular Motion and Gravitation — IB (International Baccalaureate) IB Physics HL Practice Questions Online
This page contains 149 practice MCQs for the chapter Circular Motion and Gravitation in IB (International Baccalaureate) IB Physics HL. The questions are organized by difficulty — 50 easy, 72 medium, 27 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.