University of Texas - PHY 317

mined by allowing the bullet to pass through two rotating paper disks mounted a distance

72 cm apart on the same axle. From the angular displacement 16.9 ^? of the two bul- let holes in the disks and the rotational speed 1005 rev/min of the disks, we can determine the speed of the bullet.

A dentist’s drill starts from rest. After 7.28 s

of constant angular acceleration it turns at a rate of 10140 rev/min.

Find the drill’s angular acceleration.

=                             ·        ·

 2. 72 cm What is the speed of the bullet?

7.28 s

rev

.

60 s

?

3. An electric motor rotating a workshop grind-

ing wheel at a rate of 168 rev/min is switched off. Assume constant angular deceleration of

2

× 1 rev 100 cm 60 s

magnitude 1.77 rad/s .

=                          .                                       wheel turn before it finally comes to rest?

4. A small wheel of radius 2.1 cm drives a large wheel of radius 13.2 cm by having their cir- cumferences pressed together.

If the small wheel turns at 473 rad/s, how fast does the larger one turn?

5. In the spin cycle of a washing machine, the

tub of radius 0.419 m develops a speed of 663 rpm.

What is the maximum linear speed with which water leaves the machine?

6. The driver of a car traveling at 30.1 m/s ap-

plies the brakes and undergoes a constant deceleration of 2.38 m/s².

How many revolutions does each tire make

before the car comes to a stop, assuming that the car does not skid and that the tires have radii of 0.22 m?