#### Transcript of Chapter 12 Practice 4

**Chapter 12 Practice 4**

Statics

What is d to make this balance?

1.4 m

If Fo is 90 N. What are F1 and F2 if the object is in equilibrium?

270 N

180 N

The 3.0-m-long, 100 kg rigid beam in the following figure is supported at each end. An 86 kg student stands 2.0 m from support 1.

770 N

1100 N

A 3.0-m -long ladder, leans against a frictionless wall. The coefficient of static friction between the ladder and the floor is 0.46. What is the smallest angle before the ladder falls?

47.4

A 120-cm-wide sign hangs from a 5.4 kg , 200-cm-long pole. A cable of negligible mass supports the end of the rod as shown in the figure. What is the maximum mass of the sign if the maximum tension in the cable without breaking is 400 N ?

42 kg

A car tire is 63.0 cm in diameter. The car is traveling at a speed of 23.0 m/s .

What is the tire's rotation frequency, in rpm?

What is the speed of a point at the top edge of the tire?

46 m/s

697 rpm

A hollow spherical shell with mass 2.50 kg rolls without slipping down a slope that makes an angle of 37.0 with the horizontal. Find the magnitude of the acceleration of the center of mass of the spherical shell.

Find the magnitude of the frictional force acting on the spherical shell.

5.9 N

3.54 m/s^2

Pivot points make no sense to me. Could you please do some examples/demonstrate what it would look like?

why does there have to be two pivot points to have stability?

Why is it that in static equilibrium problems that you can choose your pivot point

In the Bo problem, how does net force differ from the sum of the torque forces?

why in the world does Torque point perpendicular to the spinning object? Could you explain how the cross product makes the direction so strange?

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