#### Transcript of Chapter 12 Practice 5

**Chapter 12 Practice 5**

Momentum

A merry-go-round is a common piece of playground equipment. A 3.0 m diameter merry go round with a mass of 250 kg is spinning at 20 rpm. John runs tangent to the merry go round at 5.0 m/s, in the same direction that it is turning, and jumps onto the outer edge. John's mass is 30 kg. What is the merry go round's angular velocity, in rpm, after John jumps on?

22.3 rpm

A 200 g, 40 cm diameter turntable rotates on frictionless bearings at 60 rpm. A 20 g block sits at the center of the turntable. A compressed spring shoots the block radially outward along a frictionless groove in the surface of the turntable. What is the turntable's rotation angular velocity when the block reaches the outer edge?

50 rpm

Find the cross products AxB and CxD.

21.2 in

24 out

A 1.3 kg ball on the end of a lightweight rod is located at (x, y) = (3.0 m, 2.0 m), where the y-axis is vertical. The other end of the rod is attached to a pivot at (x, y) = (0 m, 3.0 m).

what is the torque about the pivot?

-38 k

What is the magnitude of the angular momentum of the 3.10 kg , 5.70-cm-diameter rotating disk rotating at 600 rpm?

.0791 kg m^2 /s

How fast, in rpm, would a 4.0 kg , 26-cm-diameter bowling ball have to spin to have an angular momentum of 0.17 kg m^2 / s ?

60 rpm

Force F =−10j N is exerted on a particle at r =(6i + 5j)m. What is the torque

0,0,-60 Nm

A potter's wheel, with rotational inertia 19 kg·m2, is spinning freely at 40 rpm. The potter drops a lump of clay onto the wheel, where it sticks a distance 1.2 m from the rotational axis. If the subsequent angular speed of the wheel and clay is 32 rpm what is the mass of the clay?

3.3 kg

"The order of the vectors in a cross product problem has not relation to the resultant vector it produces"

"Can we review the cross product method?"

"can we go over how inertia relates to how fast an object goes down a hill?"

In scenarios A, B, and D, the cable is attached halfway between the midpoint and end of the pole. In C, the cable is attached to the mid-point of the pole. In E and F, the cable is attached to the end of the pole.

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