Deck 10: Projectile and Satellite Motion

Question 1

Dr. Chuck projects a ball horizontally from a lab bench. The ball lands on a bullseye marked on the floor a horizontal distance equal to the ball's initial speed

A)multiplied by its time in the air.
B)coupled with its speed of fall.
C)squared plus its downward speed squared when hitting the floor.
D)all of the above
E)none of the above

Answer 1

multiplied by its time in the air.

Question 2

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

A)less than 0.5 s.
B)0.5 s.
C)more than 0.5 s.

Answer 2

0.5 s.

Question 3

A ball is tossed upward. Neglecting air drag, the acceleration along its path is

A)0 g.
B)g downward.
C)g upward.
D)g upward, then g downward.
E)none of the above

Answer 3

g downward.

Question 4

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

A)30°
B)45°
C)50°
D)75°
E)90°

Question 5

A ball rolled along a horizontal surface maintains a constant speed because

A)its velocity remains constant.
B)no horizontal force acts on it.
C)of inertia.

Question 6

An object is dropped and freely falls to the ground with acceleration g. If it is thrown upward at an angle instead, neglecting air drag, the acceleration along its path will be

A)less than g.
B)the same.
C)more than g.

Question 7

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?

A)the one dropped
B)the one fired
C)both hit at the same time.

Question 8

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

A)greater than at the top of its path.
B)less than at the top of its path.
C)the same as at the top of its path.

Question 9

While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its horizontal component of velocity

A)increases.
B)remains unchanged.
C)decreases.

Question 10

As soon as a ball rolls off the edge of a table

A)it is not acted on by any forces.
B)it is not acted on by any horizontal forces.
C)has a zero net force acting on it.
D)none of the above

Question 11

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

A)rolling ball.
B)dropped ball.
C)both hit at the same time

Question 12

As soon as a bowling ball rolls off the edge of a table its horizontal component of velocity

A)decreases.
B)remains constant.
C)increases.

Question 13

Dr. Chuck projects a ball horizontally from a lab bench. If the projection speed of the ball were greater, the time in the air would be

A)less.
B)the same.
C)greater.

Question 14

A dropped ball gains speed because

A)its velocity changes.
B)a gravitational force acts on it.
C)of inertia.
D)its nature is to become closer to Earth.

Question 15

Dr. Chuck projects a ball horizontally from a lab bench. The ball lands on a bullseye marked on the floor a horizontal distance away. Compared to the time for the ball to simply drop vertically from the bench, the time in the air for Dr. Chuck's projected ball is

A)less.
B)the same.
C)greater.

Question 16

A ball is thrown upward and caught when it returns. Compared with its initial speed and in the presence of air resistance, the speed with which it is caught is

A)more.
B)less.
C)the same.
D)need more information.

Question 17

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

A)the one dropped
B)the one fired
C)both hit at the same time.

Question 18

While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity

A)increases.
B)remains unchanged.
C)decreases.

Question 19

A projectile is fired into the air at an angle of 50° above ground level and hits a target downrange. It will also hit the target if fired at an angle of

A)40°.
B)45°.
C)55°.
D)60°.
E)none of the above

Question 20

Nellie tosses a ball upward at an angle. Assuming no air resistance, which component of velocity changes with time?

A)the horizontal component
B)the vertical component
C)both of these
D)neither of these

Question 21

A bullet is fired horizontally with an initial velocity of 300 m/s from a 20-m high tower. If air resistance is negligible, the bullet hits downrange about

A)200 m.
B)300 m.
C)400 m.
D)500 m.
E)600 m.

Question 22

An object is thrown vertically into the air. In this case air resistance affects motion. Compared with its time for ascent, the time for its descent is

A)shorter.
B)the same.
C)longer.
D)need more information

Question 23

If you throw a stone horizontally from the top of a cliff, one second after leaving your hand its vertical distance below the top of the cliff is

A)5 m.
B)10 m.
C)15 m.

Question 24

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

A)30°.
B)60°.
C)both hit at the same time

Question 25

A bullet fired horizontally from a rifle begins to fall

A)as soon as it leaves the barrel.
B)after air friction reduces its speed.
C)neither of these

Question 26

An Earth satellite is simply a projectile

A)freely falling around Earth.
B)floating motionless in space near Earth.
C)approaching Earth from outer space.

Question 27

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

A)their tangential velocities.
B)their vast distances from the Sun.
C)the inverse-square law.
D)their relatively small masses.
E)the fact that they are beyond the main gravitation of the Sun.

Question 28

Hang time is the time your feet are off the ground in a jump. If you jump upward inside a moving vehicle, your hang time will be

A)slightly more.
B)the same.
C)slightly less.

Question 29

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

A)less than 50 m/s.
B)50 m/s.
C)more than 50 m/s.

Question 30

When air drag affects the motion of projectiles, they don't travel

A)as high.
B)as far.
C)both of these
D)neither of these

Question 31

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

A)less than 50 m/s.
B)50 m/s.
C)more than 50 m/s.

Question 32

The tangential velocity of an Earth satellite is its velocity

A)parallel to the surface of Earth.
B)perpendicular to the surface of Earth.
C)attributed to satellites moving in any direction.

Question 33

The radial velocity of an Earth satellite is its velocity

A)parallel to the surface of Earth.
B)perpendicular to the surface of Earth.
C)attributed to satellites moving in any direction.
D)none of the above

Question 34

Ideally, a ball is thrown up at an angle and lands downrange. Because of air resistance, the distance reached is

A)less.
B)the same.
C)greater.
D)need more information

Question 35

A ball player wishes to determine pitching speed by throwing a ball horizontally from an elevation 5 m above ground level. The ball lands 20 m downrange. The player's pitching speed is about

A)5 m/s.
B)10 m/s.
C)20 m/s.
D)25 m/s.
E)none of the above

Question 36

It there were no gravity a stone thrown upward at 45 degrees would follow a straight-line path. But because of gravity, at the end of 1 second, the stone is actually

A)5 m below the straight line.
B)10 m below the straight line.
C)15 m below the straight line.

Question 37

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?

A)50 m
B)98 m
C)100 m
D)490 m
E)none of the above

Question 38

The paths of fragments of fireworks are

A)normally straight lines.
B)parabolas.
C)different from the paths of projectiles.

Question 39

While an airplane flies at 40 m/s at an altitude of 500 meters, the pilot drops a heavy package that falls to the ground. Neglecting air drag, about where does the package land relative to the plane flying above?

A)directly beneath the plane
B)400 m behind the plane
C)500 m behind the plane
D)more than 500 m behind the plane
E)none of the above

Question 40

The Moon does not crash into Earth because

A)Earth's gravitational field is relatively weak at the Moon.
B)gravitational pull of other planets keeps the Moon up.
C)Moon has a sufficient tangential speed.
D)Moon has less mass than Earth.
E)none of the above

Question 41

The fastest moving planet in a solar system is the

A)smallest planet.
B)most massive planet.
C)planet nearest the Sun.
D)planet farthest from the Sun.
E)all move at the same speed.

Question 42

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

A)atmosphere.
B)gravitational field.
C)both of these

Question 43

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

A)parabolic.
B)elliptical.
C)circular.
D)geosynchronous.

Question 44

The Early Bird communication satellite hovers over the same point on Earth's equator indefinitely, because

A)other forces than Earth's gravity act on it.
B)it pulls as hard on Earth as Earth pulls on it.
C)it is beyond the main pull of Earth gravity.
D)it is kept aloft by ground control.
E)its orbital period is 24 hours.

Question 45

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

A)slower.
B)faster.
C)the same.
D)need more information

Question 46

The period of an Earth satellite depends on the satellite's

A)mass.
B)weight on Earth.
C)radial distance from Earth.
D)all of the above
E)none of the above

Question 47

A lunar month is about 28 days. If the Moon were farther from Earth than it is now, the lunar month would be

A)less than 28 days.
B)about 28 days.
C)more than 28 days.
D)need more information

Question 48

Minimal orbit speed about Earth is about 8 km/s, and about Jupiter is

A)less than 8 km/s.
B)more than 8 km/s.
C)about 8 km/s.

Question 49

Communications and weather satellites always appear at the same place in the sky, because these satellites are

A)beyond the pull of Earth's gravitational field.
B)moving at a speed just short of escape velocity.
C)orbiting Earth with a 24-hour period.
D)stationary in space.
E)none of the above

Question 50

Minimal orbital speed about Earth is about 8 km/s, and about the Moon is

A)less than 8 km/s.
B)more than 8 km/s.
C)about 8 km/s.

Question 51

It takes Neptune a longer time to orbit the Sun than Earth does because Neptune

A)has much further to go.
B)goes much slower.
C)both of these
D)none of these

Question 52

A weightless astronaut in an orbiting satellite is

A)shielded from Earth's gravitational field.
B)beyond the pull of gravity.
C)like the satellite, pulled by Earth's gravitation.
D)none of the above

Question 53

The speeds of the planets about the Sun depend on

A)their distances from the Sun.
B)the masses of the planets.
C)their periods of rotation.
D)none of the above

Question 54

A lunar month is about 28 days. If the Moon were closer to Earth than it is now, the lunar month would be

A)less than 28 days.
B)about 28 days.
C)more than 28 days.
D)need more information

Question 55

An Earth satellite in close orbit circles Earth in about an hour and a half. How long would a satellite located as far away as the Moon take to orbit Earth?

A)the same hour and a half
B)less than an hour and a half
C)about 28 days
D)need more information
E)none of the above

Question 56

The circular path of a satellite orbiting Earth is characterized by a constant

A)speed.
B)acceleration.
C)radial distance.
D)all of the above
E)none of the above

Question 57

The speed of an Earth satellite does NOT depend on its

A)distance from Earth.
B)mass.
C)but it depends on both
D)it depends on neither

Question 58

Our Moon in Earth orbit travels fastest when it is

A)involved in an eclipse.
B)rotating.
C)revolving.
D)closest.
E)all of the above

Question 59

An astronaut at Earth's surface has a mass of 50 kg and a weight of 500 N. If she were floating freely inside a space habitat in remote space, she would have

A)no weight and less mass.
B)no weight and the same mass.
C)more weight and no mass.
D)none of the above

Question 60

What prevents satellites such as the ISS from falling?

A)gravity
B)centripetal force
C)centrifugal force
D)the absence of air drag
E)nothing

Question 61

Who envisioned the motion of planets as projectiles obeying the laws of physics?

A)Kepler
B)Newton
C)both of these
D)neither of these

Question 62

From Earth, one satellite appears to overtake another. The faster satellite is

A)higher.
B)lower.
C)smaller.
D)can't say

Question 63

Project a cannonball from atop Newton's hypothetical mountain at 8 km/s and it orbits Earth. Project it at 9 km/s and the shape of the orbit is

A)a somewhat larger circle.
B)a wide parabola.
C)an ellipse.

Question 64

According to Kepler, the paths of planets about the Sun are

A)parabolas.
B)circles.
C)straight lines.
D)ellipses.
E)none of the above

Question 65

Acceleration is greater for a satellite when it is at the

A)apogee (farthest point).
B)perigee (closest point).
C)zenith.
D)same acceleration at all of the above places.

Question 66

An Earth satellite in an elliptical orbit travels fastest when it is

A)nearest Earth.
B)farthest from Earth.
C)everywhere along its orbit.

Question 67

An Earth satellite in an elliptical orbit has its smallest speed

A)closest to Earth.
B)when getting farther from Earth.
C)when farthest from Earth.
D)need more information

Question 68

Which of these vary for satellites in elliptical orbits?

A)speed.
B)momentum.
C)kinetic energy.
D)all of the above
E)none of the above

Question 69

Consider a moon that orbits one of our most distant planets in an elliptical path. The distance that the moon covers each day is

A)greatest when closest to the planet.
B)greatest when farthest from the planet.
C)the same everywhere.
D)need more information

Question 70

When Kepler devised his laws of planetary motion, he was most influenced by

A)Galileo.
B)Newton.
C)Tycho Brahe.

Question 71

Both Newton and Kepler considered forces on the planets. Kepler mistakenly hypothesized the direction of the forces to be

A)along their directions of travel.
B)perpendicular to their directions of travel.
C)toward the Sun.
D)none of the above

Question 72

The focal point of a satellite in orbit about the Sun is

A)inside the Sun.
B)outside the Sun.
C)both of these
D)neither of these

Question 73

For all paths of Earth satellites, one focus of the path is

A)the location from which the satellite was launched.
B)Earth's center.
C)the Sun's center.
D)need more information

Question 74

The force of gravity does work on a satellite when it is in

A)circular orbit.
B)elliptical orbit.
C)both of these
D)neither of these

Question 75

The orbital path of a satellite has two focal points. When both focal points are together

A)the satellite path is an ellipse.
B)the satellite path is a circle.
C)satellites lose speed.

Question 76

A satellite in an elliptical orbit about a planet travels much faster when it is directly over a

A)large ocean.
B)large island.
C)high mountain range.
D)great plain or plateau.
E)none of the above

Question 77

Which of these vary for satellites in circular orbits?

A)speed.
B)momentum.
C)kinetic energy.
D)all of the above
E)none of the above

Question 78

Newton hypothesized that the forces acting on planets was

A)along their directions of travel.
B)perpendicular to their directions of travel.
C)toward the Sun.
D)none of the above

Question 79

Compared with the period of satellites in close Earth orbit, the period of satellites orbiting far from Earth is

A)shorter.
B)the same.
C)longer.
D)need more information

Question 80

According to Kepler, the line from the Sun to any planet sweeps out equal areas of space

A)with each complete revolution.
B)only when the paths are ellipses.
C)in equal time intervals.