Physics Chapter 4
Pioneer 10 was able to escape the solar system by
"bouncing off" Jupiter like a tennis ball bouncing off an approaching tennis racket.
Escape speed from Earth is
11.2 km/s
A softball player determines her pitching speed by throwing a ball horizontally from an elevation of 5 m above the ground. The ball lands 20 m downrange. What is her pitching speed
20m/s
A ball is thrown horizontally from the top of a tall cliff. Three seconds later, the ball has fallen a vertical distance of
45m
A stone is thrown horizontally from the top of a cliff. One second after leaving your hand it drops a vertical distance of
5m
The hang time of an athlete who moves horizontally 2.0 m during a 1.25-m-high jump is
About 1s
A satellite near Earth makes a full circle in about 90 minutes. Much farther from Earth, say at the distance to the Moon, time for a full circle would be
About 28 days
In the vacuum of outer space far from our Sun, there is no
Atmospheric pressure
If Earth's mass somehow decreased with no change in its radius, your weight would
Decrease also
An Earth satellite in an elliptical orbit travels slowest when it is
Farthest from the Earth
How far must one travel to completely be beyond Earth's gravity
Forget it; you can't travel far enough
If the radius of the Earth somehow decreased with no change in mass, your weight would
Increase
Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them
Increases
A lunar month is about 28 days. If the Moon were closer to Earth than it is now, the lunar month would be
Less than 28 days
Minimal orbit speed about Earth is about 8 km/s. Minimal orbital speed for a satellite about the Moon would be
Less than 8km/s
The force of gravity on a satellite in circular orbit doesn't change its speed because the force is
Perpendicular to its direction of motion
The radial velocity of an Earth satellite is its velocity
Perpendicular to the surface of the Earth
As a bowling ball that rolls off the edge of a table falls, its horizontal component of motion
Remains constant
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 hunter aims a rifle at an angle of 10° above the horizontal. The hunter fires a bullet while simultaneously dropping another bullet from the side of the rifle. The bullet to hit the ground first is
The dropped one
The planet Neptune was discovered by perturbations of
Uranus
If the Sun were twice as massive
both of these (its pull on the earth would double, the pull of the earth on the sun would double)
A rock is thrown upward at 50° with respect to the horizontal. As it rises, its vertical component of velocity
decreases
According to Newton, the greater the masses of interacting objects, the
greater the gravitational force between them
Perturbations of planets are due to
interplanetary forces
The Moon does not crash into Earth because
the moon has a sufficient tangential speed
Inside a freely-falling elevator your
weight is zero
Strictly speaking, when you step off a curb you are momentarily
weightless