Physics exam chapter 10 projectile and satellite motion

A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its vertical component of velocity

decreases

According to Kepler's laws, the paths of planets about the sun are

ellipses

An Earth satellite is simply a projectile

freely falling around the Earth

If a satellite's radial velocity is zero at all times, its orbit must be

circular

After a rock thrown straight up reaches the top of its path and then falls a short distance, its acceleration is (neglect air resistance)

the same as it was at the top of its path.

A gun with a muzzle velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, how far downrange will the bullet be 1 second later?

100

An airplane travels at 141 km/h toward the northeast. What is its component of velocity due north?

100 km/h

The ground speed of an airplane that has an airspeed of 200 km/h when it is in a 200-km/h crosswind is

283 km/h

A projectile is launched vertically upward at 50 m/s. If air resistance is negligible, its speed upon returning to its starting point is

50 m/s

A bullet is fired horizontally with an initial velocity of 300 m/s from a tower 20 m high. If air resistance is negligible, the horizontal distance the bullet travels before hitting the ground is about

600 m

A river 100 m wide flows due south at 1 m/s. A boat that goes 1 m/s relative to the water leaves the west bank. To land at a point due east of its starting point, the boat must be pointed

no where- it can't be done

Throw an object upward at a 45 degree angle. With no gravity it will follow a straight-line path. But because of gravity, at the end of 1 second, it is

about 5m below the straight-line

A projectile is fired vertically from the surface of the Earth at 8 km/s. The projectile will

rise and fall back to the Earth's surface

Acceleration due to gravity on the moon is less than on Earth, and the moon is smaller than Earth. So compared to an Earth satellite, a satellite in close orbit about the moon would travel

slower

Which of the following is not a vector quantity?

speed

An airplane that flies at 100 km/h in a 100 km/h hurricane crosswind has a ground speed of

141 km/h

An object is thrown vertically into the air. Because of air resistance, the time for its descent will be

longer than the ascent time.

Without air resistance, a projectile fired horizontally at 8 km/s from atop a mountain would

- accelerate downward at g as it moves horizontally. - trace a curve that matches the earth's curvature. - return later to its starting position and repeat its falling behavior.

A bullet fired horizontally over level ground hits the ground in 0.5 second. If it had been fired with twice the speed in the same direction, it would have hit the ground in

0.5 s

What prevents satellites such as the space shuttle from falling?

Nothing; they are continually falling as they orbit the Earth.

A ball player wishes to determine pitching speed by throwing a ball horizontally from an elevation of 5 m above the ground. The player sees the ball land 20 m down range. What is the player's pitching speed?

about 20 m/s

A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?

the dropped one

An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward at an angle instead, its acceleration will be

1 g downward

A river 100 m wide flows due south at 1 m/s. A boat that goes 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat reaches the east bank

100 m farther south than where it started

A river 100 m wide flows due south. A boat that goes 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat crosses in

100 s

A river 100 m wide flows due south. A boat that goes 1 m/s relative to the water is pointed due east as it crosses from the west bank. Relative to the Earth, the boat travels

141 m

Two projectiles are fired from ground level at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. The projectile to hit the ground first will be the one fired at (neglect air resistance)

30 dgrees

A projectile is fired into the air at an angle of 50 degrees with the ground and lands on a target that is at the same level at which the projectile started. It will also land on the target if it is fired at an angle of

40 degrees

A stone is thrown horizontally from the top of a cliff. One second after it has left your hand, its vertical distance below the top of the cliff is

5 m

A projectile is launched at ground level an angle of 15 degrees above the horizontal and lands down range. What other projection angle for the same speed would produce the same down-range distance?

75 degrees

Both Newton and Kepler considered forces on the planets. Kepler hypothesized the direction of the forces was

along their directions of travel

A bullet fired horizontally from a rifle begins to fall

as soon as it leaves the barrel

Earth satellites are typically more than 100 km high so as to be above the Earth's

atmosphere

An airplane flies at 40 m/s at an altitude of 50 meters. The pilot drops a heavy package which falls to the ground. Where, approximately, does the package land relative to the plane's new position?

beneath the plane

A projectile is fired horizontally in a region of no air resistance. The projectile maintains its horizontal component of velocity because

it is not acted on by any horizontal forces.

The tangential velocity of an Earth satellite is its velocity

parallel to the surface of the Earth.

The radial velocity of an Earth satellite is its velocity

perpendicular to the surface of the Earth.

Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity

remains constant

A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its horizontal component of velocity

remains unchanged

A hunter on level ground fires a bullet at an angle of 2 degrees below the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?

the fired one

Planets would crash into the sun if it weren't for

their tangential velocities