Chapter 6 (PART 2) Flashcards Preview

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Flashcards in Chapter 6 (PART 2) Deck (9):
1

(a) If the KE of an arrow is tripled, by what factor has its speed increased?

(b) If the speed is doubled, by what factor does its KE increase?

(a) 1.73

(b) 4

2

How much work must be done to stop a 1050 kg car traveling at 106 km/h?

-455162.0 J

3

An 83 g arrow is fired from a bow whose string exerts an average force of 95 N on the arrow over a distance of 79 cm. What is the speed of the arrow as it leaves the bow?

42.5 m/s

4

If the speed of a car is increased by 80%, by what factor will its minimum braking distance be increased, assuming all else is the same? Ignore the driver's reaction time.

3.24

5

In starting an exercise, a 1.6 m tall person lifts a 2.10 kg book on the ground so it is 1.80 m above the ground.

(a) What is the potential energy of the book relative to the ground?

(b) What is the potential energy of the book relative to the top of the person's head?

(c) How is the work done by the person related to the answers in parts (a) and (b)? (Select all that apply.)
-The work done is related, but not equal to the answer in (a).
-The work done is equal to the answer in (a).
-The work done is equal to the answer in (b).
-The work done is related, but not equal to the answer in (b).

(a) 37.094 J

(b) 4.116 J

(c) -The work done is equal to the answer in (a).
-The work done is related, but not equal to the answer in (b).

6

A ski starts from rest and slides down a 28° incline 110 m long. Use energy methods.

(a) If the coefficient of friction is 0.09, what is the ski's speed at the base of the incline?

(b) If the snow is level at the foot of the incline and has the same coefficient of friction, how far will the ski travel along the level?

(a) 29.0 m/s

(b) 476.8 m

7

Suppose the roller coaster in the figure below (h1 = 31 m, h2 = 10 m, h3 = 20) passes point 1 with a speed of 1.90 m/s. If the average force of friction is equal to one fourth of its weight, with what speed will it reach point 2? The distance traveled is 35.0 m.

http://www.webassign.net/giancoli/6-41alt.gif

21.0 m/s

8

An elevator cable breaks when a 764 kg elevator is 29.2 m above a huge spring (k = 8.00 ✕ 104 N/m) at the bottom of the shaft.

(a) Calculate the work done by gravity on the elevator before it hits the spring.

(b) Calculate the speed of the elevator just before striking the spring.

(c) Calculate the amount the spring compresses (note that work is done by both the spring and gravity in this part).

(a) 218626.24 J

(b) 23.9 m/s

(c) 2.43 m

9

If you stand on a bathroom scale, the spring inside the scale compresses 0.50 mm, and it tells you your weight is 700 N. Now if you jump on the scale from a height of 0.60 m, what does the scale read at its peak?

34292.86 N