Download Ch.4 Questions Holt Physics key page 2

4 REVIEW & ASSESS
NEWTON'S
SECOND A N D THIRD LAWS
R e v i e w questions
13. because Earth has a very large
mass
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13. Earth is attracted to an object with a force equal to
14. An object with greater mass
requires a larger force for a
given acceleration because it
has more inertia than an
object with less mass.
gnd opposite the force Earth exerts on the object.
Explain why Earth's acceleration is not equal to and
22. Two forces are applied to a car in a
erate i t , as shown i n Figure 4-30.
a. What is the resultant o f these
b. I f the car has a mass o f 3200 k
tion does it have? (Disregard
(See Sample Problem 4B.)
opposite that o f the object.
14. Explain Newton's second law in terms o f inertia.
15. One-sixth of the force needed
to lift an object on Earth is
needed on the moon.
15. ; A n astronaut on the m o o n has a 110 kg crate and a
450 N
10.0°' \ /
/
380N
230 kg crate. H o w do the forces required to lift the
16. on the horse: the force of the
cart, F^down, F„ up, a reaction force of the ground on
the hooves; on the cart: the
force of the horse, F,,down, F„
up, kinetic friction
17. push it gently; With a smaller
force, the astronaut will experience a smaller reaction force.
\
crates straight up on the m o o n compare w i t h the
/
forces required to lift them on Earth?
16. Draw a force diagram to identif)' all the actionreaction pairs that exist for a horse pulling a cart.
C o n c e p t u a l questions
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23. A 3.00 kg ball is dropped from the
17. A space explorer is m o v i n g through space far from
18. As the climber exerts a force
downward, the rope supplies a
reaction force that is directed
upward, \^'hen this reaction
force is greater than the
climber's weight, the climber
accelerates upward.
horizontal wind exerts a constant f
specimen from an alien planet, floating around the
the ball.
cabin o f the ship. Should the explorer push it gently
a. H o w long does it take to hit t
or kick i t toward the storage compartment? Wliy?
b. H o w far from the building
18. Explain why a rope climber must pull downward on
the rope in order to move upward. Discuss the force
exerted by the climber's arms in relation to the
19. a. zero, as long as the speed is
constant
b. zero
weight o f the climber during the various stages o f
each "step" up the rope.
20. 3.52 m/s-
19. A n 1850 kg car is moving to the right at a constant
21. 4.7X lO^s
speed o f 1.44 m/s.
22. a. 770 N a t 8.13° to the right
of forward
b. 0.241 m/s^ at 8.13° to the
right o f forward
a. What is the net force on the car?
b. Wliat would be the net force on the car i f it were
moving to the left?
23. a. 6.00 s
b. 72.0 m
c. 63.6 m/s
176.4 m high. While the ball is fa
any planet or star and notices a large rock, taken as a
the ground?
c. What is its speed when it hits
(See Sample Problem 48.)
24. A 40.0 kg wagon is towed up a h i l l
w i t h respect to the horizontal. The
allel to the incline and exerts a forc
wagon. Assume that the wagon st
the bottom of the hill, and disregar
a. H o w fast
30.0 m up
b. H o w fast
80.0 m up
is the wagon goi
the hill?
is the wagon goi
the hill?
Practice problems
(See Sample Problem 4B.)
20. What acceleration w i l l you give to a 24.3 kg box i f
24. a. 4.78 m/s
b. 7.80 m/s
you push it with a force o f 85.5 N?.
(See Sample Problem 4B.)
25. a. 2.3 m
b. 1.8 m
25. A shopper in a supermarket push
cart w i t h a horizontal force o f 12 N
a. H o w far w i l l the cart move
21. A freight train has a mass o f 1.5 x 10^ kg. I f the loco-
from rest? (Disregard friction
motive can exert a constant pull o f 7.5 x 10 N , how
b. H o w far w i l l the cart move in
long would it take to increase the speed o f the train
per places an 85 N child in
from rest to 85 km/h? (Disregard friction.)
pushing?
(See Sample Problem 4B.)
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Chapter 4
(See Sample Problem 4B.)