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