Circular Motion Mixed Quiz 1

A torque is applied to a nut, using a wrench.

Which change will increase the magnitude of applied torque?

A student wants to evaluate the relationship between centripetal force and speed. The student connects a tennis ball to a rope, and swings it in a circle horizontally.
Which of the following needs to be kept constant to ensure a valid experiment?

A 15-gram metal ball bearing on a string is swung around a pole in a circle of radius 0.8 m. The plane of the circular path is horizontal. The angular velocity of the motion is 4π rad/s^–1.

What is the magnitude of the centripetal force required to maintain the motion of the ball?

A satellite is orbiting a planet at a fixed altitude.
Which row of the table correctly identifies the magnitude of the work done by the forces on the satellite and the reason for this being the case?

A horizontal disc is rotating clockwise on a table when viewed from above. Two small blocks are attached to the disc at different radii from the centre.

Draw a diagram of this scenario, using vector arrows to show the relative linear velocities and centripetal forces for each block as the disc rotates. (3 marks)

A toy car was placed facing outwards on a rotating turntable. The car was held in place by a force sensor connected to the centre of the turntable. The centre of mass of the car was 0.25 metres from the centre of the turntable. The reading from the force sensor was recorded at varying speeds of rotation. A stopwatch was used to time the rotation of the turntable. The linear velocity was calculated from the period of rotation. The graph shows the force on the car versus the square of the linear velocity of the car.

(a) Use the graph to determine the mass of the car. (3 marks)

(b) Identify possible errors in the data and outline how to reduce their effects on the estimation of the mass of the car. (4 marks)

In the 1840s, French physicist, Hippolyte Fizeau performed an experiment to measure the speed of light. He shone an intense light source at a mirror 8 km away and broke up the light beam with a rotating cogwheel. He adjusted the speed of rotation of the wheel until the reflected light beam could no longer be seen returning through the gaps in the cogwheel.

The diagram shows a similar experiment. The cogwheel has 50 teeth and 50 gaps of the same width.

Explain why specific speeds of rotation of the cogwheel will completely block the returning light. Support your answer with calculations. (5 marks)