Page 78 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 5] LAWS OF MOTION 63

5.7. A force of 1.0 lb acts on a 1.0-slug object that can move freely. The object’s acceleration is
(a) 0.031 ft/s 2 (c) 1.0 ft/s 2
(b) 0.5 ft/s 2 (d) 32 ft/s 2
5.8. A force of 1.0 lb acts on a 1.0-lb object that can move freely. The object’s acceleration is
(a) 0.031 ft/s 2 (c) 1.0 ft/s 2
(b) 0.5 ft/s 2 (d) 32 ft/s 2

5.9. Four hundred grams of salami weighs
(a) 0.041 N (c) 400 N
(b) 3.9 N (d) 3.9 kN

2
5.10. A force that gives a 2.0-kg object an acceleration of 1.6 m/s would give an 8.0-kg object an acceleration of
(a) 0.2 m/s 2 (c) 1.6 m/s 2
(b) 0.4 m/s 2 (d) 6.4 m/s 2

5.11. A 20-kg crate is lifted by an upward force of 200 N. The crate’s upward acceleration is

(a) 0.20 m/s 2 (c) 10 m/s 2
(b) 9 m/s 2 (d) 98 m/s 2

5.12. A vehicle slows down from 50 to 15 ft/s in 10 s when its brakes exert a force of 200 lb on it. The vehicle weighs
approximately
(a) 57 lb (c) 1830 lb
(b) 560 lb (d) 22,400 lb

5.13. A bicycle and its rider together have a mass of 80 kg. If the bicycle’s velocity is 6 m/s, the force needed to bring it to
a stop in4sis
(a) 12 N (c) 120 N
(b) 53 N (d) 1176 N

5.14. A 5.0-kg object, initially at rest, is acted on by a net force of 3.0 N for 3.0 s. During that time the object moves
(a) 0.3 m (c) 1.8 m
(b) 0.9 m (d) 2.7 m

5.15. A 300-g ball at rest is struck with a bat with a force of 150 N. If the bat was in contact with the ball for 0.020 s, the
ball’s velocity is

(a) 0.01 m/s (c) 2.5 m/s
(b) 0.1 m/s (d) 10 m/s

Supplementary Problems

5.1. Since action and reaction forces are always equal in magnitude and opposite in direction, how can anything ever be
accelerated?
5.2. A horse is pulling a cart. (a) What is the force that causes the horse to move forward? (b) What is the force that causes
the cart to move forward?