Rotational Motion

A fan blade, initially at rest, rotates with a constant acceleration of 0.025 rad/s². What is the time interval required for it to reach a 4.2 rad displacement after starting from rest   

• 1.8 s
• 2.0 s
• 16 s
• 18 s

A gear spins at a rate of 400 revolutions/minute. Which choice is closest to its angular speed in radians/second?

• 6.67 rad/s

• 2500 rad/s

• 41.9 rad/s

• 20.9 rad/s

Which has greater linear 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

A tire of 68cm in diameter travels 9.2km. How many revolutions does it make?

• 43.00 rads
• 567 revs
• 4300 revs
• 68cm

A 0.12-m-radius grinding wheel takes 5.5 s to speed up from 2.0 rad/s to 11.0 rad/s. What is the wheel's average angular acceleration?

• 9.6 rad/s/s

• 4.8 rad/s/s

• 3.1 rad/s/s

• 1.6 rad/s/s

A 0.50-kg toy is attached to the end of a 1.0-m very light string.  The toy is whirled in a horizontal circular path on a frictionless tabletop.  If the maximum tension that the string can withstand without breaking is 350 N.  What is the maximum speed the mass can have without breaking the string?

• 700 m/s
• 26 m/s
• 13 m/s
• 19 m/s

Tags

NGSS.HS-PS2-1

A 2.0-kg ball is moving with a constant speed of 5.0 m/s in a horizontal circle whose diameter is 1.0 m. What is the magnitude of the net force on the ball?

• 50 N
• 20 N
• 0 N
• 100 N

Tags

NGSS.HS-PS2-1

Two equal-magnitude forces are applied to a door at the doorknob. The first force is applied perpendicular to the door, and the second force is applied at 30° to the plane of the door. Which force exerts the greater torque about the door hinge?

• A) the first force (applied perpendicular to the door)

• B) the second force (applied at an angle)

• C) Both forces exert zero torque.

• D) Both forces exert equal non-zero torques.

A force of 17 N is applied to the end of a 0.63-m long torque wrench at an angle 45° from a line joining the pivot point to the handle. What is the magnitude of the torque about the pivot point produced by this force?

• A) 10.7 N ∙ m

• B) 9.7 N ∙ m

• C) 12.0 N ∙ m

• D) 7.6 N ∙ m

The figure shows a person's foot. In that figure, the Achilles tendon exerts a force of magnitude F = 720 N. What is the magnitude of the torque that this force produces about the ankle joint?

• A) 26 N ∙ m

• B) 36 N ∙ m

• C) 16 N ∙ m

• D) 21 N ∙ m