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Physics chapter 7

Terms in this set (23)

When an object is moving with uniform circular motion, the object's tangential speed
Is constant
The centripetal force on an object in circular motion is
in the same direction as the centripetal acceleration.
A ball is whirled on a string, then the string breaks. What causes the ball to move off in a straight line
Inertia
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 the Earth and the apple
When calculating the gravitational force between two extended bodies, you should measure the distance
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 = 6.673 10 11 N•m2/kg2)
4.0 N
n the figure above, according to Kepler's laws of planetary motion
If t1= t2,thenA1=A2.
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 t = square root [G (m/r)] .
What does m represent in this equation?
The mass of the central object
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.
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 x 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
A heavy bank-vault door is opened by the application of a force of
3.0 102 N directed perpendicular to the plane of the door at a distance of 0.80 m from the hinges. What is the torque?
A lever
Which of the following is not a valid equation for mechanical advantage
MA=Wout/Win
What term describes a change in the speed of an object in circular motion?
Tangential acceleration
When a car makes a sharp left turn, what causes the passengers to move toward the right side of the car?
Inertia
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
Which of the following statements is correct?
The farther the force is from the axis of rotation, the more torque
is produced
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?
30.1 cm
An iron bar is used to lift a slab of cement. The force applied to lift the slab is 4.0 x 10^2 N. If the slab weighs 6400 N, what is the mechanical advantage of the bar?
16
Earth exerts a 1.0 N gravitational force on an apple. What is the magnitude of the gravitational force the apple exerts on Earth?
1.0 N
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