Physics final

A projectile is launched vertically at 100 m/s. If air resistance can be ignored, at what speed will it return to its initial level? -0 m/s -10 m/s -200 m/s -100 m/s

100 m/s

About how far below a straight-line path does a satellite in close Earth orbit fall in the first second of fall? -Zero meters -10 meters -Depends on the projected speed -5 meters

5 meters

How far below a straight-line path does a horizontally projected projectile fall in the first second of fall? -5 meters -Zero meters -Depends on the projected speed -10 meters

5 meters

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? -10 m, 20 m -5 m, 10 m -5 m, 20 m -10 m, 40 m

5m, 20m

How can a projectile "fall around the Earth"? -In a circular orbit around a spherical planet, the force and the fall are always toward the center. -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. -All of the above

All of the above

What exactly is a projectile? An object that continues in motion by its own inertia An object with no air resistance An object with independent horizontal and vertical components of motion An object that follows a parabolic trajectory

An object that continues in motion by its own inertia

Why does the vertical component of velocity for a projectile change with time whereas the horizontal component of velocity doesn't change? Air resistance can be ignored. The projectile has horizontal inertia but not vertical inertia. The projectile has vertical inertia but not horizontal inertia. Gravity is a purely vertical force.

Gravity is purely a vertical force.

Why does the force of gravity change the speed of a satellite in an elliptical orbit? The force of gravity is always tangent to the satellite motion. Gravity slows the satellite as it moves away and speeds it up on its return. Gravity speeds up the satellite as it moves away and slows it on its return. The force of gravity is always perpendicular to the satellite motion.

Gravity slows the satellite as it moves away and speeds it up on its return.

At what part of an elliptical orbit does an Earth satellite have the greatest speed? The lowest speed? -It travels at a constant 8 km/s. -Greatest at the focus inside Earth; lowest at the other focus -Greatest nearest Earth; lowest furthest from Earth -Lowest nearest Earth; greatest furthest from Earth

Greatest nearest Earth, lowest furthest from Earth

A stone is thrown upward at an angle. What happens to the magnitude of the vertical component of its velocity as it rises? As it falls? -It decreases while rising, but it increases while falling. -Rising or falling, it does not change. -It increases while rising, but it decreases while falling. -It decreases while rising and while falling.

It decreases while rising, but it increases while falling

A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises? As it falls? -It increases while rising, but it decreases while falling. -It decreases while rising, but it increases while falling. -Rising or falling, it does not change. -It increases while rising and while falling.

Rising or falling, it does not change

Why doesn't the force of gravity change the speed of a satellite in circular orbit? The inertia of the fast satellite is so great that gravity can be ignored. The force is at a right angle to the velocity. Air resistance counteracts the effects of gravity. Satellites orbit at a height where gravity is essentially zero.

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 an elliptical orbit but not in a circular orbit. Kinetic energy is constant for both orbits. The force of gravity is perpendicular to the motion in a circular orbit but not in an elliptical orbit. Kinetic energy is not constant for a satellite in a circular orbit but it is 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

Is the sum of kinetic and potential energies a constant for satellites in circular orbits, in elliptical orbits, or in both? Elliptical only Neither Both Circular only

both

Bull's-eye Bob at a hunting range fires his rifle at a target 240 meters downrange. The bullet moves horizontally from the rifle barrel with a speed of 400 m/s. -How far does the bullet drop from a straight-line horizontal path by the time it reaches the target?

d= 1.8 m 240/400= .6 d=1/2gt^2 d=(1/2)(9.8)(.6)^2 d=1.8 m

The horizontal and vertical components of velocity for a projectile are ______ -equal for angles greater than 45° -parts of a parabola -independent of each other -dependent on each other

independent of eachother

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. more. the same. need more information.

less

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

remains unchanged