Uniform Circular Motion - UNSOLVED PRACTICE SET

Q7. Define uniform circular motion. Give two examples from everyday life — one from nature and one from a machine or device.

Q8. Why is uniform circular motion considered accelerated motion even though the speed is constant? What is the name and direction of the acceleration involved?

Q9. A stone is tied to a string and whirled in a horizontal circle at constant speed.
(a) What happens to the stone if the string breaks suddenly?
(b) In what direction does the stone fly off, and why?

Q10. What is the difference between speed and velocity in uniform circular motion? Explain why one is constant and the other is not.

Q11. The Earth revolves around the Sun approximately in a circular path.
(a) Is this uniform circular motion?
 (b) What provides the centripetal force?
(c) In what direction is the Earth's velocity at any given moment?

Q12. A wheel of radius 0.5 m rotates so that a point on its rim completes 2 revolutions per second. Calculate
(a) the distance covered by the rim point in 1 second, and
(b) the speed of the rim point.

Q13. Explain in detail why uniform circular motion is an example of accelerated motion. Your answer must include:
(a) the definition of acceleration in terms of velocity change,
(b) why velocity changes even at constant speed in circular motion,
(c) the name, formula, and direction of centripetal acceleration,
(d) what provides centripetal force in the case of a satellite orbiting Earth, and
(e) one example where the centripetal force is suddenly removed — what happens and why

Q14. A cyclist rides a bicycle around a circular park of radius 35 m at a constant speed, completing one full round in 22 seconds.
(a) Calculate the circumference of the park.
(b) Calculate the speed of the cyclist.
(c) What is the displacement of the cyclist after one full round?
(d) What is the displacement after exactly half a round?
(e) Is the average velocity for one full round zero? Explain what this tells us about circular motion.

Q15. Compare uniform circular motion and uniform linear (rectilinear) motion under the following heads:
(a) constancy of speed,
(b) constancy of velocity,
(c) presence or absence of acceleration,
(d) direction of acceleration, and
(e) the type of path traced. Give one real-life example of each.

Q16. An athlete runs on a circular track of radius 56 m at a constant speed. She completes one round in 44 seconds.
(a) Calculate the total distance (circumference) of the track.
(b) Calculate her speed.
(c) What is her displacement after one complete round?
(d) What is her displacement after exactly half a round?
(e) Calculate the magnitude of her average velocity for the half-round journey.

Q17. The minute hand of a clock is 10 cm long.
(a) How far does the tip of the minute hand travel in 1 hour?
(b) What is the speed of the tip in cm/s?
(c) What is the displacement of the tip after 30 minutes (from the 12 o'clock position to the 6 o'clock position)?
(d) Calculate the average velocity (magnitude) of the tip over 30 minutes.

Q18. A spacecraft is orbiting Earth in a circular orbit. The radius of the orbit is 6,800 km and the spacecraft completes one orbit in 96 minutes.
(a) Calculate the orbital circumference in km.
(b) Calculate the orbital speed in km/s.
(c) Is the speed of the spacecraft constant? Is its velocity constant? Explain the difference.
(d) What would happen to the spacecraft if the gravitational force suddenly disappeared?