assignment for Crackcode only!!!

1

Ivy Bucsa

PHY-102

August 10, 2014

Lillian Flakes

Assignments for Chapter 3 and Chapter 4

Think and Solve Chapter 3

55. Judy (mass 40 kg), standing on slippery ice, catches her dog Atti ( mass 15 kg) leaping toward her at 3.0 m/s. Use conservation of momentum to show that the speed of Judy and her dog after the catch is 0.8 .m

57. A 5-kg fish swimming at 1 m/s swallows an absentminded 1-kg fish swimming toward it at a velocity that brings both fish to halt. Show that the speed of the smaller fish before lunch was 5 m/s.

59. A simple lever is used to lift a heavy load. When a 60-N

force pushes one end of the lever down 1.2 m, the load

rises 0.2 m. Show that the weight of the load is 360 N

64. Show that 480 W of power is expended by a weightlifter

when lifting a 60-kg barbell a vertical distance of 1.2 m

in a time interval of 1.5 s.

Chapter 4

Exercise

68. The balls have different masses and speeds. Rank the following

from greatest to least: (a) momentum and (b) the

impulses needed to stop the balls

72. The roller coaster ride starts from rest at point A. Rank

these quantities from greatest to least at each point A–E:

(a) speed, (b) KE, and (c) PE.

A

B

C

Read and Check

7. Where do you weigh more: at sea level or on top of one of

the peaks of the Rocky Mountains? Defend your answer

Discussion Questions

94. Newton tells us that gravitational force acts on all bodies

in proportion to their masses. Why, then, doesn’t a

heavy body fall faster than a light body?

98. A friend says that astronauts inside the International

Space Station are weightless because they’re beyond the

pull of Earth’s gravity. Correct your friend’s ignorance.

110. A park ranger wants to shoot a monkey hanging from

a branch of a tree with a tranquilizing dart. The ranger

aims directly at the monkey, not realizing that the dart

will follow a parabolic path and thus will fall below the

monkey. The monkey, however, sees the dart leave the

gun and lets go of the branch to avoid being hit. Will

the monkey be hit anyway? Does the velocity of the dart

affect your answer, assuming that it is great enough to

travel the horizontal distance to the tree before hitting

the ground? Defend your answer.