Physics 2021 Quiz Questions and answers

• Two people are riding merry-go-round. Person 1 is sitting at the edge, person 2 - halfway between center of merry-go-round and its edge. If the merry-go-round is rotating at constant rate, what will be the ratio of angular velocities of person 1 to angular velocity of person 2?

  1
• Two people are riding merry-go-round. Person 1 is sitting at the edge, person 2 - halfway between center of merry-go-round and its edge. If the merry-go-round is rotating increasing angular speed, what is the ratio of tangential acceleration of person 1 to tangential acceleration of person 2?

  2
• Two people are riding merry-go-round. Person 1 is sitting at the edge, person 2 - halfway between center of merry-go-round and its edge. If the merry-go-round is rotating at constant rate, what will be the ratio of linear velocities of person 1 to velocity of person 2?

  2
• You are watching from above the merry-go-round, it rotates clockwise and slows down (draw a picture!). Direction of angular velocity is

  downward
• You are watching from above the merry-go-round, it rotates clockwise and slows down (draw a picture!). Direction of angular acceleration is

  Upward
• Sphere 1 has mass 2M and radius R. Sphere 2 has mass M and radius 2R. If rotational inertia of the sphere 1 is I, what is rotational inertia of second sphere in terms of I?

  2I
• Consider two objects, one is solid sphere, another solid cylinder. Both of them have the same radius and the same mass. We can conclude that rotational inertia of a cylinder is compared to a sphere...

  Larger than the rotational inertia of a sphere
• Consider a rod of mass M and length L. For this rod, the ratio of rotational inertia relatively the end to the rotational inertia relatively to the center is:

  4
• Consider a hoop of radius R and mass M. For this hoop, the ratio of rotational inertia relatively the center to the rotational inertia relatively to the axis of rotation at distance R from the center is:

  1/2
• Figure shows a solid flat disk of radius R with a circular hole of radius R/2. Three points are indicated. Rank these points according to rotational inertia of the disk around a perpendicular to the disk axis, greatest first.

  c > a > b

  
• Two solid spheres are rolling down from incline without slipping. Sphere 1 has mass 2M and radius R. Sphere 2 has mass M and radius 2R.Which of these two will make it to the bottom first?

  They will make it to the bottom at the same time
• Two solid spheres are rolling down from incline without slipping. Sphere 1 has mass 2M and radius R. Sphere 2 has mass M and radius 2R.Which of these two will have a greater angular velocity at the bottom?

  Sphere 1
• A flat solid disk of radius R and mass M is rotating around vertical axel going through a center of mass of a disk. Suddenly a hoop of mass M and radius R is falling coaxially on the disk. Hoop did not rotate initially. If moment of inertia of rotating system initially was I, what is rotational inertia of a system after hoop has landed?

  3I
• A flat solid disk of radius R and mass M is rotating around vertical axel going through a center of mass of a disk. Suddenly a hoop of mass M and radius R is falling coaxially on the disk. Hoop did not rotate initially. If the angular momentum of a system was initially L, what is the angular momentum after the hoop has landed?

  L
• A flat solid disk of radius R and mass M is rotating around vertical axel going through a center of mass of a disk. Suddenly a hoop of mass M and radius R is falling coaxially on the disk. Hoop did not rotate initially. If angular velocity of the system was initially ω, what is angular velocity of the system after hoop has landed?

  ω/3
• A person weighing 800 N stands with one foot on each of two bathroom scales. Which statement is definitely true?

  If one scale reads 500 N, the other will read 300 N.
• A lever is 5.0 m long. The distance from the fulcrum to the weight to be lifted is 1.0 m. If a 3000 N rock is to be lifted, how much force must be exerted on the lever?

  750 N
• A massless scaffold is held up by a wire at each end. The scaffold is 12 m long. A 300 N-box sits 4.0 m from the left end. What is the tension in each wire?

  Left wire 200 N, right wire 100 N
• The scaffold in previous example weighs 200 N now. Everything else is the same. What is the tension in each wire?

  Left wire 300 N, Right wire 200 N
• You are balancing a book and several weights with equal-arm balance. After equilibrium was reached, you are stepping into elevator moving up. When equilibrium will be broken?

  Equilibrium will not be broken
• A piece of wood is floating in a bathtub. A tiny piece of steel sits on top of it, and does not touch the water. If the piece of steel is taken off and placed into the water, what happens to the water level in the tub?

  It goes down
• A steel ball sinks in water but floats in a pool of mercury. Where is the buoyant force on the ball greater?

  floating on the mercury
• An object floats with half its volume beneath the surface of the water. The weight of the displaced water is 2000 N. What is the weight of the object?

  2000 N
• A 10-kg piece of aluminum, sits at the bottom of a lake, right next to a 10 kg piece of lead. Which has the greater buoyant force on it?

  Aluminum
• You are initially 1.0 m beneath the surface of a pool. If you dive to 2.0 m beneath the surface, what happens to the absolute pressure on you?

  It less than doubles
• A mass oscillates at the end of a spring, both on earth and on the moon. Where the period the greatest?

  Same on both
• A mass on a spring undergoes SHM. When the mass is at maximum displacement from equilibrium, its instantaneous acceleration

  is a maximum
• Doubling only amplitude of a vibrating mass-and-spring system produces what effect on the system's mechanical energy?

  Increases the energy by a factor of 4
• Simple pendulum A swings back and forth at twice the frequency of simple pendulum B. Which statement is correct?

  The length of B is four times the length of A
• Water flows through a pipe with speed of 18 m/s. Pipe suddenly widens to 3 times of its initial diameter. The speed of water in broader part of a pipe is:

  2 m/s