PHS 112 Chapter 4 Homework Study Guide
Escape speed from Earth is
11.2 km/s
With no air resistance, a projectile fired at 60 degrees has the same range as if it were fired at
30 degrees
Phil stands at rest with both feet on a scale that reads 500 N. After he gently lifts one foot, the scale reads
500 N
What is the force of gravity on a 500-N woman standing on Earth's surface?
500 N
A projectile is launched at an angle of 15 degrees above the horizontal and land downrange. With no air resistance, what other projection angle for the same speed would produce the same downrange distance?
75 degrees
What is the magnitude of the gravitational force between Earth and a 1-kg body at its surface?
9.8 N
The Universal Gravitational Constant G was first measured by
Cavendish
How does the force of gravity between two bodies change when the distance between them is tripled?
It is 1/9 of the initial force
Chuck Stone releases a ball near the top of a track and measures the ball's speed as it rolls horizontally off the end of the table. Students make measurements to predict where a can must be placed to catch the ball
Since the ball leaves the table horizontally, its speed will not affect the time it takes to reach the floor
Is there change in the force of gravity between two objects when their masses are doubled and the distance between them is also doubled?
There is no change
If Earth's mass somehow doubles with no change in its size, and your mass remains the same, your weight
also doubles
If your mass doubles, your weight
also doubles
A ball rolls off the edge of a table at the same time another ball drops vertically from the same table. The ball to hit the floor first is the
both hit at the same time
Which of the following kinematic equations correctly describes the horizontal distance d between the ball and the cart at the moment the ball lands? The cart's initial horizontal velocity is v0x, its horizontal acceleration is ax, and t is the time elapsed between launch and impact.
d=1/2 azt^2; four times as far
How will doubling the initial upward speed of the ball change the time the ball speeds in the air? A kinematic equation may be helpful here. The time in the air will
double
In accord with the inverse-square law, half as far means _______ __________ the force
four times
An Earth satellite is simply a projectile
freely falling around the earth
According to Newton, the greater the masses of interacting objects, the
greater the gravitational force between them
In accord with the inverse-square law, twice as far means _______-_______________ the force
one-quarter
The tangential velocity of an Earth satellite is its velocity
parallel to the surface of Earth
A projectile that is fired vertically at 5 km/s from the Earth's surface will
rise and fall back to Earth's surface
A projectile that is fired vertically at 8 km/s from Earth's surface will
rise and fall back to Earth's surface
Newton discovered
that gravity is universal
After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)
the same as it was at the top of its path
Without air resistance, a projectile fired horizontally at 8 km/s from a mountaintop will
trace a curve that matches Earth's curvature, return to its starting position and repeat its falling behavior, and accelerate downward at g as it moves horizontally
Consider two planets in space that gravitationally attract each other. If the mass of one planet are doubled, and the distance between them is also doubled, then the force between them is
twice as much
Inside a freely-falling elevator, you would have no
weight
An airplane flying overhead drops a care package directly over Mike at rest in his Corvette. Neglecting air resistance, the package will land
well ahead of Mike and his Corvette
A "weightless" astronaut in an orbiting space vehicle is
without a support force
