Unit 7: Rotational Kinematics

Which has greater angular speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?

• The inside horse
• The outside horse
• Neither - they both have the same angular speed

A fan spins with a constant angular speed of 500 radians/second. How long will it take to cover an angle of 2π radians (one revolution)?

• 0.013 s

• 0.002 s

• 76.9 s

• 6.28 s

You apply force to a wrench to tighten a bolt. The wrench breaks in half. Select the best answer for what happens next. Assume the force applied remains constant.

• The torque is now half of what it was, because torque and distance are inversely proportional
• The torque is now half of what it was, because torque and distance are directly proportional
• The torque is now double of what it was, because torque and distance are inversely proportional
• The torque is now double of what it was, because torque and distance are directly proportional

A disk initially rotating counterclockwise (CCW) at a certain constant angular speed is suddenly being pulled on by two strings T₁ and T₂, where T₂ > T_1. What is going to happen next?

• The disk will continued rotating CCW at the constant angular speed.

• The disk will continued rotating CCW but it will speed up

• The disk will slow down and start rotating CW

• The disk will eventually stop rotating

Tags

NGSS.HS-PS2-1

How do you find the tangential speed of a rotating circle?

• v = ωr
• v = ωr²
• v = ωπ
• v = ωπr

How do you get the maximum torque?

• longer lever arm and more force at an acute angle
• shorter lever arm with more force perpendicularly
• shorter lever arm and more force perpendicularly
• longer lever arm with more force perpendicularly

Looking at the picture, which way will it rotate?

• Clockwise
• Counter clockwise
• Neither

Tags

NGSS.HS-PS2-1

The easiest way to open a heavy door  is by applying the force

• Near the hinges
• In the middle of the door
• At the edge of the door far from the hinges
• At the top of the door

Two wheels are fixed to each other and are free to rotate about a frictionless axis through their concentric centers. Four forces are exerted tangentially to the wheels. As a result of the net torque on the wheels, the wheels will rotate-

• clockwise

• counterclockwise

A seesaw is unbalanced with two people of different masses sitting equal distances from the center. Which of the following will result in equilibrium?

• The larger person moving further away from the center.
• Moving the smaller person closer to the center.
• Moving the smaller person further from the center.
• Making the larger person do nothing.

Tags

NGSS.HS-PS2-1