Physics H - Chapter 10

Projectile Motion

any object projected by some means and continues in motion by its own inertia and is only acted on by gravity

Kepler’s Laws of Planetary Motion #1

"The orbit of every planet is an ellipse with the Sun at one of the two foci"

Kepler’s Laws of Planetary Motion #2

"A line joining a planet and the Sun sweeps out equal areas during equal intervals of time"

Kepler’s Laws of Planetary Motion #3

"The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit"

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

no horizontal force acts on it

A dropped ball gains speed because…

a gravitational force acts on it

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

the vertical component

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

remains constant

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

it is acted on by any horizontal forces

A balls 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

While a rock thrown upward at 50 degrees to horizontal, its vertical component of velocity ____ BEFORE it reaches the maximum height. (no air resist.)

decreases

While a rock thrown upward at 50 degree angle to horizontal, its vertical component of velocity ____ AFTER it reaches the maximum height. (no air resist.)

decreases

While a rock thrown upward at 50 degrees, its horizontal component of velocity… (no air resist.)

remains unchanged

Dr. Chuck projects a ball horizontally from a lab bench. The ball lands on a target on the floor a horizontal distance equal to the balls initial speed…

multiplied by its time in the air

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…

the same

After a rock thrown straight up reaches the top of its path and then falls a short distance, its acceleration is… (no air resist.)

the same as at the top of its path

An object is dropped and freely falls to the ground with acceleration g. If it is thrown upward at and angle instead, the acceleration along its path will be… (no air resist.)

the same

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…

less

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…

5 m

The paths of fragments of fireworks are…

parabolas

When air drag affects the motion of projectiles, the don’t travel…

as high, and as far

A ball is tossed upward. The acceleration along its path is… (no air resist.)

g downward

A projectile is launched vertically upward at 50 m/s. Its speed upon returning to its starting point is… (no air resist.)

50 m/s

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…

less than 50 m/s

An Earth satellite is simply a projectile…

freely falling around Earth

The tangential velocity of an Earth satellite is its velocity…

parallel to the surface of Earth

The radial velocity of an Earth satellite is its velocity…

perpendicular to the surface of Earth

The Moon does not crash into Earth because…

Moon has a sufficient tangential speed

Planets would crash into the Sun if it weren’t for…

their tangential velocities

The fastest moving planet in a solar system is the…

planet nearest the sun (Mercury)

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

atmosphere

Our Moon in Earth orbit travels fastest when it is…

closest

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

no weight and the same mass

The speed of an Earth satellite does NOT depend on its…

mass

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

less than 28 days

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

speed, acceleration and radial distance

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

circular

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

less than 8 km/s

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

more than 8 km/s

The period of an Earth satellite depends on the satellite’s…

radial distance from Earth

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

it’s orbital period is 24 hours

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

orbiting Earth with a 24-hour period

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

longer

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

lower

What varies for satellites in elliptical orbits?

speed, momentum and kinetic energy

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

nearest Earth

Acceleration is greater for a satellite when it is at the…

perigee (closest point)

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

greatest when closest to the planet

Project a cannonball from atop Newton’s hypothetical mountain at 8 km/s and it…

orbits Earth

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…

an ellipse

An Earth satellite in an elliptical orbit has its smallest speed…

When farthest from Earth

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

Earth’s center

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

the satellite path is a circle

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

Tycho Brahe

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

ellipses

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

Newton

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

in equal time intervals

According to Kepler, the orbital period of a planet is directly proportional to the…

cube of the planet’s average distance from the Sun

According to Kepler, the speed of a planet is slowest when it is…

farthest from the Sun

Newton hypothesized that the forces acting on planets was…

towards the Sun

The conservation of energy applies to satellites in…

circular and elliptical orbit

When the potential energy of a satellite decreases…

its kinetic energy correspondingly increases

The kinetic energy if a planet is maximum when it is…

closest to the Sun

Angular momentum is conserved for a satellite in…

circular and elliptical orbit

Angular momentum is greater for a satellite when it is at the…

apogee(farthest point) AND perigee(nearest point)