Physics Chapter 10
During soccer practice, Maya kicked a soccer ball 37° off the ground at 25 m/s. Max, the goalie, caught the ball 60 m away from Maya and 1.0 m off the ground. What was the velocity of the ball when Max caught it?
(20 m/s)i^ - (14 m/s)j^
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
0.5 s
What is the ratio of escape speed from Earth to circular orbital speed? Ignore air resistance.
1.41
Escape speed from Earth is any speed equal to or greater than __________.
11.2 km/s
During soccer practice, Maya kicked a soccer ball 37° off the ground at 25 m/s. What was the ball's speed 2.2 s after she kicked it?
21 m/s
During soccer practice, Maya kicked a soccer ball 37° off the ground at 25 m/s. Max, the goalie, caught the ball 60 m away from Maya and 1.0 m off the ground. Max caught the ball ______ s after Maya kicked it.
3.0
A projectile falls beneath the straight-line path it would follow if there were no gravity. How many meters does it fall below this line if it has been traveling for 1 s? For 2 s?
5 m, 20 m
About how far below a straight-line path does a satellite in close Earth orbit fall in the first second of fall?
5 meters
How far below a straight-line path does a horizontally projected projectile fall in the first second of fall?
5 meters
A projectile is launched at 30° above ground level. What other angle at the same speed will result in the same range?
60°
When Dr. Hewitt releases the two projectiles, which one hits the ground first?
Both balls hit the ground at the same time.
Why do the two objects hit the table at the relative times that they do?
Gravity pulls the same amount on both, and they both drop the same distance.
At what part of an elliptical orbit does an Earth satellite have the greatest speed? The lowest speed?
Greatest nearest Earth; lowest furthest from Earth
You're in an airplane that flies horizontally with speed 1200 km/h (320 m/s ) when an engine falls off. Neglecting air resistance, assume it takes 35 s for the engine to hit the ground. Find the height of airplane.
H = 6.0 km
The Moon does not crash into Earth because
Moon has a sufficient tangential speed.
For an Earth satellite in circular orbit, list all the values that do not change.
Only speed, gravitational force, and distance from Earth
For an Earth satellite in an elliptical orbit, list all the values that do change.
Speed, gravitational force, and distance from Earth
Why doesn't the force of gravity change the speed of a satellite in circular orbit?
The force is at a right angle to the velocity.
Why is kinetic energy a constant for a satellite in a circular orbit but not for a satellite in an elliptical orbit?
The force of gravity is perpendicular to the motion in a circular orbit but not in an elliptical orbit.
How can a projectile "fall around the Earth"?
The projectile falls 5 m for every 8 km and so does Earth. A projectile can "fall around Earth" if the distance it falls matches the curvature of Earth. In a circular orbit around a spherical planet, the force and the fall are always toward the center.
When Dr. Hewitt releases the two objects, how can we tell whether one of the objects hits the ground first or whether they both hit at the same time?
We are able to hear the two balls fall.
A dropped ball gains speed because
a gravitational force acts on it.
When air drag affects the motion of projectiles, they don't travel
as high and as far
A bullet fired horizontally from a rifle begins to fall
as soon as it leaves the barrel
The kinetic energy of a satellite remains constant when the satellite follows a __________.
circular path
The kinetic energy of a planet is maximum when it is
closest to the sun
You're in an airplane that flies horizontally with speed 1200 km/h (320 m/s ) when an engine falls off. Neglecting air resistance, assume it takes 35 s for the engine to hit the ground. Find the horizontal distance that the aircraft engine falls.
d = 11 km
You're in an airplane that flies horizontally with speed 1200 km/h (320 m/s ) when an engine falls off. Neglecting air resistance, assume it takes 35 s for the engine to hit the ground. If the airplane somehow continues to fly as if nothing had happened, what is the distance between the engine and the airplane at the moment the engine hits the ground?
d = 6.0 km
During soccer practice, Maya kicked a soccer ball 37° off the ground at 25 m/s. At t = 2.2 s after she kicked the ball, was it moving upward in its trajectory, downward in its trajectory, or was it at the apex of its trajectory?
downward
According to Kepler, the paths of planets about the Sun are
ellipses
Kepler was the first to be credited for discovering that planets follow __________.
elliptical paths
An Earth satellite is simply a projectile
freely falling around Earth
The horizontal and vertical components of velocity for a projectile are __________.
independent of each other
A weightless astronaut in an orbiting satellite is
like the satellite, pulled by Earth's gravitation.
The foci of the elliptical path for an Earth satellite are __________.
one at Earth's center and the other elsewhere
The period of an Earth satellite depends on the satellite's
radial distance from Earth
As soon as a bowling ball rolls off the edge of a table its horizontal component of velocity
remains constant
Angular momentum is greater for a satellite when it is at the
same at apogee and perigee
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 (neglect air resistance)
the same as at the top of its path
A ball is thrown horizontally from a cliff at a speed of 10 m/s . You predict that its speed 1 s later will be slightly greater than 14 m/s . Your friend says it will be 10 m/s. Who is correct?
you!
