Download Chapter 6 Study Guide

Chapter 6 and 7 Study Guide
Vocabulary. Know the following terms.
Chapter 6
Uniform circular motion
centripetal force
centripetal acceleration
projectile
Chapter 7
gravitational force
Kepler’s 1st Law
trajectory
Kepler’s 2nd Law
Kepler’s 3rd Law
Topics to Know
Section 5.3
1. Describe the two types of friction.
2. Describe the condition of equilibrium of a moving object.
3. A crate weighing 562 N is resting on a plane inclined 30.0o above the horizontal.
Find the component of the weight forces that are parallel and perpendicular to the
plane. (parallel = 281 N; perpendicular = 487 N)
4. A force of 40.0 N accelerates a 5.0 kg block at 6.0 m/s2 along a horizontal surface.
(a) What kind of friction is this and how large is the frictional force? (b) What is
the coefficient of friction? ( kinetic, 10 N; 0.20)
5. A 62 kg person on skis is going down a hill sloped at 37o. The coefficient of
kinetic friction between skis and the snow is 0.15. How fast is the skier going
5.0 s after starting from rest? (23.6 m/s)
6. A 62 kg person on skis is going down a hill sloped at 37o. The coefficient of
kinetic friction between the skis and the snow is 0.15. How fast is the skier going
5.0 s after starting from rest? (24 m/s)
7. Bobbie, who has a mass of 45 kg, starts down a slide that is inclined at an angle of
45o with the horizontal. If the coefficient of kinetic friction between Bobbie’s
shorts and the slide is 0.25, what is her acceleration? (5.2 m/s2)
Section 6.1
1) What are the direction and magnitude of the velocity vectors at the height of a
projectile’s path?
2) What is the velocity of an object at the height of its trajectory?
3) Would the acceleration of a projectile in the horizontal direction still be zero if air
friction is considered?
4) What is the term used to describe the time a projectile remains in the air?
5) What is the acceleration of a projectile during its flight?
6) What is the equation that gives us the displacement in the horizontal direction?
7) How should we consider the motion of a projectile in the vertical direction?
8) A long jumper leaves the ground at an angle of 20.0o to the horizontal and at a
speed of 11.0 m/s. (a) How far does he jump? (Assume that his motion is
equivalent to that of a particle.) (b) What maximum height is reached?
(7.94 m; 0.722 m)
9) A stone is thrown horizontally at a speed of 5.0 m/s from the top of a cliff that is
78.4 m high. (a) How long does it take the stone to reach the bottom of the cliff?
(b) How far from the base of the cliff does the stone hit the ground? (c) What are
the horizontal and vertical components of the stone’s velocity just before it hits
the ground? (4.00s; 20 m; vx = 5.0 m/s vy = 39.2 m/s)
10) A ball is launched at 4.5 m/s at 66o above the horizontal. What are the maximum
height and flight time of the ball? (0.86 m; 0.84 s)
11) You took a running leap off a high-diving platform. You were running at 2.8 m/s
and hit the water 2.6 s later. How high was the platform, and how far from the
edge of the platform did you hit the water. Ignore air resistance?
( platform = 33 m high; 7.3 m)
12) A 1.60 m tall girl throws a football at an angle of 41.0o from the horizontal and at
an initial velocity of 9.40 m/s How far away from the girl will it land?
( 10.5 m)
Section 6.2
1) An object moving in a circular path, has a linear velocity pointing in which direction?
2) What is the direction of the centripetal acceleration?
3) The acceleration of an object in uniform circular motion is called ____________.
4) Give two examples of centripetal forces. Describe the situation in which they
serve as centripetal forces.
5) How do we define the period of an object’s rotation?
6) What are the two things an object wants to do as it moves around a circular path?
What will determine which of these two things actually occurs?
7) Write an expression for Newton’s 2nd law that incorporates centripetal
acceleration?
8) A 13 g rubber stopper is attached to a 0.93 m string. The stopper is swung in a
horizontal circle, making one revolution in 1.18 s. Find the tension force exerted
by the string on the stopper. (0.342 N)
9) A dragonfly is sitting on a merry-go-round 2.8 m from the center. If the tangential
velocity of the ride is 0.89 m/s, what is the centripetal acceleration of the dragon?
( 0.28 m/s2)
10) An athlete whirls a 7.00 kg hammer 1.8 m from the axis of rotation in a horizontal
circle. If the hammer makes one revolution in 1.0 s, what is the centripetal
acceleration of the hammer? What is the tension in the chain?
( 71 m/s2; 5.0x102 N)
Section 7.1
1. How is Kepler’s 1st Law related to Newton’s Universal Law of Gravitation?
2. Is the proportionality constant (K) dependent on the mass of the orbiting body?
Section 7.2
1. How is the gravitational force between two objects related to the distance between
them?
2. Why is it that two people do not feel the gravitational force between them?
3. What happens to the gravitational acceleration of the Earth the farther we move
from the surface of the Earth? Why?
4. What did Henry Cavendish’s experiment show?
5. Three 0.300 kg billiard balls are placed on a table at the corners of a right triangle.
Find the net gravitational force on the cue ball (designated as m1) resulting from
the other two balls if the cue ball is between the other two. The distance between
one ball and the cue ball is 0.400 m and the distance between the cue ball and the
other ball is 0.300m. (7.65x10-11 N)
A. Two bowling balls each have a mass of 6.3 kg. They are located next to each
other with their centers 16.5 cm apart. What gravitational force do they exert on
each other? Assume G = 6.67×10-11 N·m2/kg2. (9.7x10-8 N)