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physics chapter 7
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Gravity
Terms in this set (44)
When an object is moving with uniform circular motion, the object's tangential speed
is constant
When an object is moving with uniform circular motion, the centripetal acceleration of the object
is directed toward the center of motion.
What term describes a change in the speed of an object in circular motion?
tangential acceleration
What is the term for the net force directed toward the center of an object's circular path?
centripetal force
Which of the following can be a centripetal force?
friction,gravity,tension
The centripetal force on an object in circular motion is
in the plane of the object's motion and perpendicular to the tangential speed.
The centripetal force on an object in circular motion is
in the same direction as the centripetal acceleration.
A child rides a bicycle in a circular path with a radius of 2.0 m. The tangential speed of the bicycle is 2.0 m/s. The combined mass of the bicycle and the child is 43 kg.
What is the magnitude of the bicycle's centripetal acceleration?
2.0 m/s^2
A child rides a bicycle in a circular path with a radius of 2.0 m. The tangential speed of the bicycle is 2.0 m/s. The combined mass of the bicycle and the child is 43 kg.
What is the magnitude of the centripetal force on the bicycle?
86N
A child rides a bicycle in a circular path with a radius of 2.0 m. The tangential speed of the bicycle is 2.0 m/s. The combined mass of the bicycle and the child is 43 kg.
What kind of force provides the centripetal force on the bicycle?
friction
When a car makes a sharp left turn, what causes the passengers to move toward the right side of the car?
inertia
A ball is whirled on a string, then the string breaks. What causes the ball to move off in a straight line?
inertia
Tides are caused by
differences in the gravitational force of the moon at different points on Earth.
Why does an astronaut weigh less on the moon than on Earth?
The gravitational field strength is less on the moon's surface than on Earth's surface.
If you lift an apple from the ground to some point above the ground, the gravitational potential energy in the system increases. This potential energy is stored in
the gravitational field between Earth and the apple.
An object's tendency to resist acceleration is measured by the object's
inertial mass.
The degree to which an object attracts other objects is measured by the object's
gravitational mass.
Which of the following confirms that gravitational mass and inertial mass are equivalent?
Free-fall acceleration is the same at all points where the gravitational field strength is the same.
In this text, which of the following symbols represents gravitational field strength?
G
this text, which of the following symbols represents the constant of universal gravitation?
Select one:
G
When calculating the gravitational force between two extended bodies, you should measure the distance
from the center of each body.
The gravitational force between two masses is 36 N. What is the gravitational force if the distance between them is tripled?
G=6.673X10^-11
4.0 N
Two small masses that are 10.0 cm apart attract each other with a force of 10.0 N. When they are 5.0 cm apart, these masses will attract each other with what force?
40.0 N
Kepler developed his laws of planetary motion as he tried to reconcile
Select one:
Copernican theory with Tycho Brahe's data.
Until the middle of the 16th century, most people believed ____ was at the center of the universe.
earth
Newton's law of universal gravitation
can be used to derive Kepler's third law of planetary motion.
The equation for the speed of an object in circular orbit is What does m represent in this equation?
mass of the central object
How would the speed of Earth's orbit around the sun change if Earth's distance from the sun increased by 4 times?
it would decrease by a factor of 2.
How would the speed of Earth's orbit around the sun change if Earth's mass increased by 4 times?
It would increase by a factor of 2.
When an astronaut in orbit experiences apparent weightlessness,
the net gravitational force on the astronaut is not balanced by a normal force.
Which of the following quantities measures the ability of a force to rotate or accelerate an object around an axis?
torque
Where should a force be applied on a lever arm to produce the most torque?
farthest from the axis of rotation
If you want to open a swinging door with the least amount of force, where should you push on the door?
as far from the hinges as possible
If you cannot exert enough force to loosen a bolt with a wrench, which of the following should you do?
Use a wrench with a longer handle.
Suppose a doorknob is placed at the center of a door. Compared with a door whose knob is located at the edge, what amount of force must be applied to this door to produce the torque exerted on the other door?
two times as much
A heavy bank-vault door is opened by the application of a force of 3.0 ´ 10 ^2 N directed perpendicular to the plane of the door at a distance of 0.80 m from the hinges. What is the torque?
240 N•m
If the torque required to loosen a nut on a wheel has a magnitude of 40.0 N·m and the force exerted by a mechanic is 133 N, how far from the nut must the mechanic apply the force?
Select one:
30.1 cm
What kind of simple machine are you using if you pry a nail from a board with the back of a hammer?
lever
girl pushes a box that has a mass of 450 N up an incline. If the girl exerts a force of 150 N along the incline, what is the mechanical advantage of the incline?
Select one:
3.0
An iron bar is used to lift a slab of cement. The force applied to lift the slab is 4.0 ´ 10^2 N. If the slab weighs 6400 N, what is the mechanical advantage of the bar?
16
What is the efficiency of a machine that requires 1.00 ´ 10^2 J of input energy to do 35 J of work?
35%
A box weighing 210 N is pushed up an inclined plane that is 2.0 m long. A force of 140 N is required. If the box is lifted 1.0 m, what is the efficiency of the inclined plane?
75%
What quantity measures the output force of a machine relative to the input force?
mechanical advantage
What quantity measures the work done by a machine relative to the work done on a machine?
efficiency
THIS SET IS OFTEN IN FOLDERS WITH...
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