Chapter 10 Projectile Motion Review
A bullet is fired 10 degrees above the horizontal while another bullet is simultaneously dropped from the level of the rifle. Which bullet will hit the ground first?
The dropped one will hit first
A bullet is fired 10 degrees below the horizontal while another bullet is simultaneously dropped from the level of the rifle. Which bullet will hit the ground first?
The one that is fired
Is a satellite coasting at constant speed in a circular orbit accelerating?
Yes, speed may be constant, but direction is changing
An object is dropped and freely falls to the ground with acceleration g. If it is thrown downward at an angle instead, neglecting air drag, the acceleration along its path will be
acceleration is always g (in downward direction)
According to Kepler, the speed of a planet is the fastest when it is
closest to the Sun
According to Kepler, the paths of planets about the SUn are
ellipses
An Earth satellite in an elliptical orbit travels the slowest when it is
farthest from Earth near the apogee
Why does a dropped ball gain speed?
gravitational force acts on it
Describe the forces acting on a ball as it rolls off the edge of the table
gravitational forces ONLY
The acceleration of a thrown rock at the top of its path is always
gravity
The forces at work in an elliptical orbit are due to
gravity
When any object is thrown upward, neglecting air resistance, the acceleration along its path is
gravity working downward 10 m/s
Describe how the horizontal component of velocity will change when a projectile thrown up into the air at ANY angle above the horizontal rise, neglecting air drag
horizontal will remain constant
Hang time
is the time your feet are off the ground in a jump
Ideally, a ball is thrown up at an angle and lands downrange, Because of air resistance, the distance reached is
less
A projectile is launched vertically upward at 10 m/s If air resistance does affect motion, then its speed upon returning to its starting point is
less than 10 m/s
If air resistance is present, then the speed of the ball that is caught will be
less than the speed of the ball as it is thrown up into the air
Speed, Acceleration, and Kinetic Energy is greater for a satellite when it is at the
perigee
apogee
potential energy is greatest when the satellite is farthest away
perigee
potential energy is least when the satellite is closest
1 s
5 m, 10 m/s
A projectile is launched from ground level at 30 degrees above the horizontal and lands downrange. What other projectile angle for the same speed would produce the same down-range distance?
60 degrees
In order for a satellite to have an elliptical orbit it must have a speed
8 km/s higher than 8 km/s
4 s
80 m, 40 m/s
A projectile is launched vertically upward at 10 m/s. If air resistance is negligible, its speed upon returning to its starting point is
If no air resistance than returning speed will equal initial speed= 10 m/s
What happens to KE when the potential energy of a satellite decreases?
It increases
Of the planets in the Solar System,
Mercury moves the fastest because it is the closest to the Sun
Why does a ball rolled along a horizontal surface maintains a constant speed?
No horizontal force acts on it
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 seconds/ Vertically
If a rock that has been thrown horizontally from the top of a cliff landed 20 m from the cliff, how much time did the rock spend in the air?
2 s
2 s
20 m, 20 m/s
A projectile is fired into the air at an angle of 55 above ground level and hits a target downrange. It will also hit the target if fired at an angle of
35 degrees
Two projectiles are fired from ground level at equal speeds but different angles. One is fired at an angle of 35 degrees and the other at 55 degrees. Neglecting air resistance, the projectile to hit the ground first will be the one fired at
35 degrees
If there were no gravity a stone thrown upward at 45 degrees would follow a straight-lin path. But because of gravity, at the end of 3 seconds, the stone is actually
45 m below the straight-line
3s
45 m, 30 m/s
Why do satellites not crash into the Earth?
Because they have sufficient tangential speed
Which will hit the ground first? A ball projected horizontally from a lab table or a ball that is just dropped?
They will be in the air the same amount of time
In the above scenario, which one will travel farther?
They will have the same range.
Two balls are projected horizontally from a lab bench. One travels at 2 m/s, the other at 4 m/s. Which ball will be in the air the longest? Which will hit the ground first?
They will hit the ground at the same time
As soon as a bowling ball rolls off the edge of a table, what happens to its horizontal component of velocity?
remains constant
Which ball hits first? A ball rolls off the edge of a table at the same time another ball drops vertically from the same table
same time they will hit
A projectile that falls freely around the Earth is called a
satellite
The Moon would crash into the Earth if it weren't for its
tangential velocities
Air drag will decrease both
the heigh and range of a projectile
How does a person's mass and weight change in space?
the person's weight would be 0 and their masses would be the same
If you jump upward inside a moving airplane, your hang time will be
the same as if you jumped on the ground
When a ball is thrown upward at an angle. Assuming no air resistance, which component of velocity changes with time?
vertical component
Describe how the vertical component of velocity will change when a projectile thrown up into the air at ANY angle above the horizontal rise, neglecting air drag
vertical component will decrease as it reaches the top