Clicker Questions exam 3 physics

Two equal-mass particles (A and B) are located at some distance from each other. Particle A is held stationary while B is moved away at speed v. What happens to the center of mass of the two-particle system? A.It does not move B.It moves away from A with speed v C.It moves away from A with speed v/2

C.It moves away from A with speed v/2

Dr. Lannon is talking in a normal voice at 65 dB. Approximately how loud (in dB) will it be when everyone in our class (25 persons) talks normally and continuously at the same time? A.75 dB B.80 dB C.90 dB D.93 dB

B. 80dB

You are sitting on a freely rotating bar-stool with your arms stretched out and a heavy glass mug in each hand. Your friend gives you a twist and you start rotating around a vertical axis though the center of the stool. You can assume that the bearing the stool turns on is frictionless, and that there is no net external torque present once you have started spinning. What happens to your angular velocity as you pull in your arms?

it increases

You are sitting on a freely rotating bar-stool with your arms stretched out and a heavy glass mug in each hand. Your friend gives you a twist and you start rotating around a vertical axis though the center of the stool. You can assume that the bearing the stool turns on is frictionless, and that there is no net external torque present once you have started spinning. What happens to your kinetic energy as you pull in your arms?

it increases

A 75 kg painter stands at the center of a 50. kg 3.0 meter plank. The supports are 1 meter in from each edge. Calculate the force on support A

610N

A person raises one leg to an angle of 30 degrees. An ankle weight (89 N) attached a distance of 0.84 m from her hip. What is to torque due to this weight?

65 Nm

A person exerts a tangential force of 36.1 N on the rim of a disk-shaped merry-go-round of radius 2.74 m and mass of 167 kg. If the merry-go-round starts at rest, what is its angular speed after the person has rotated it through an angle of 32.5°?

0.423 rad/s

An object executing simple harmonic motion has a maximum speed of 4.3 m/s and a maximum acceleration of 0.65 m/s Find the amplitude of this motion. Find the period of this motion.

28m 42s

Two wheels with fixed hubs, each having a mass of 1 kg, start from rest and forces are applied as shown. Assume the hubs and spokes are massless, so that the rotational inertia is I = mR2. In order to impart identical angular accelerations, how large must F2be? A.0.25 N B.0.5 N C.1 N D.2 N E.4 N

2N

A rope of length L and mass M hangs from a ceiling. If the bottom of the rope is given a gentle wiggle, a wave will travel to the top of the rope. As the wave travels upward does its speed A.increase? B.decrease? C.stay the same?

A. Increase

Suppose a periodic wave moves through some medium. If the period of the wave is increased, what happens to the wavelength of the wave assuming the speed of the wave remains the same? A.The wavelength increases B.The wavelength remains the same C.The wavelength decreases

A. the wave length increases

A person raises one leg to an angle of 30 degrees. An ankle weight (89 N) attached a distance of 0.84 m from her hip. If she raises her leg higher, the torque due to the weight will.

Decrease

SI Unit for Torque

Nm

You are sitting on a freely rotating bar-stool with your arms stretched out and a heavy glass mug in each hand. Your friend gives you a twist and you start rotating around a vertical axis though the center of the stool. You can assume that the bearing the stool turns on is frictionless, and that there is no net external torque present once you have started spinning. What happens to your angular momentumas you pull in your arms?

it will stay the same