physics chapter 10
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 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
Escape speed from Earth is any speed equal to or greater than _______.
11.2 km/s
An airplane that flies at 100 km/h in a 100 km/h hurricane crosswind has a ground speed of
141 km/h. ( v = √[(x)^2 + (y)^2]. then v = √[(100)^2 + (100)^2] which equals 141.)
A river 100 m wide flows due south with speed 1 m/s relative to the bank. 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.
The hang time of a basketball player who jumps a vertical distance of 2 feet (0.6 m) is about 2/3 second. What will be the hang time if the player reaches the same height while jumping 4 feet (1.2 m) horizontally?
2/3 seconds (the hang time depends on vertical not horizontal)
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
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 vertically upward at 50 m/s. If air resistance is negligible, its speed upon returning to its starting point is
50 m/s.
A projectile is launched at 30° above ground level. What other angle at the same speed will result in the same range?
60°
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
When a satellite travels at a constant speed, the shape of its path is
a circle
The kinetic energy of a satellite remains constant when the satellite follows _______.
a circular path
Both Newton and Kepler considered forces on the planets. Kepler hypothesized the direction of the forces was...
along their directions of travel
A rocket coasts in an elliptical orbit around Earth. To attain the greatest amount of KE for escape using a given amount of fuel, should it fire its engines to accelerate forward when it is at the apogee or at the perigee? (Hint: Let the formula Fd=ΔKE be your guide to thinking. Suppose the thrust F is brief and of the same duration in either case. Then consider the distance d the rocket would travel during this brief burst at the apogee and at the perigee.)
at the perigee
When no air resistance acts on a fast-moving baseball, its acceleration is
downward g
The force of gravity does work on a satellite when it is in
elliptical orbit.
Would the speed of a satellite in close circular orbit about Jupiter be greater than, equal to, or less than 8 km/s?
greater than 8 km/s
Earth is closer to the Sun in December than in June. In which of these two months is Earth moving faster around the Sun?
in December
The horizontal and vertical components of velocity for a projectile are _______.
independent of each other
An object is thrown vertically into the air. Because of air resistance, the time for its descent will be
longer than the ascent time.
When you toss a projectile sideways, it curves as it falls. It will be an Earth satellite if the curve it...
matches the curved surface of Earth.
The foci of the elliptical path for an Earth satellite are _______.
one at Earth's center and the other elsewhere
When a projectile achieves escape speed from Earth, it
outruns the influence of Earth's gravity, but is never beyond it.
A rocket coasts in an elliptical orbit about the Earth. To attain escape velocity using the least amount of fuel in a brief firing time, should it fire off at the apogee, or at the perigee? (Hint: Let "Fd = change in KE" guide your thinking.)
perigee, where it is closest and fastest
The period of a satellite, the time it takes for a complete revolution, depends on the satellite's
radial distance.
Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity
remains constant
The velocity of a typical projectile can be represented by horizontal and vertical components. Assuming negligible air resistance, the horizontal component along the path of the projectile
remains the same (Since there is no force horizontally, no horizontal acceleration occurs.)
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.
Is the time taken for a complete revolution of a satellite in close orbit about the Earth is smaller or greater than for orbits of greater altitude?
smaller
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
On which does the speed of a circling satellite not depend: the mass of the satellite, the mass of Earth, or the distance of the satellite from Earth.
the mass of the satellite
Mars has about 1/9 the mass of Earth. If Mars were somehow positioned into the same orbit as Earth's, how would its time to circle the Sun compare with Earth's? (Longer, shorter, or the same?)
the same