### A car travels in a circle with constant speed. The net force on the car is\

directed towards the center of the curve.

### A satellite orbits the earth at an unchanging speed of 18,000 mph. This satellite\

both of the above.

### According to Newton, doubling the distance between two interacting objects\

divides by 4 the gravitational force between them.

### If a planet's radius decreases but the mass stays the same, the acceleration due to gravity near the surface will _____ .

increase

### If the mass of the Earth somehow increased with no change in radius, your weight would

increase also.

### Panets A and B orbit the same star. Planet B is four times further from the star than planet Aand has twice the mass of planet A. The gravitational force of the star on planet B is _____ the force on planet A.

an eighth of

### An asteroid exerts a 360-N gravitational force on a nearby spacecraft. If the spacecraft moves to a point 3 times as far from the center of the asteroid, the force will be

40 N.

### 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.

### A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, its vertical component of velocity

decreases.

### A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, its horizontal component of velocity

remains unchanged.

### Throw an object upward at a 45 degree angle. With no gravity it will follow a straight-line path. But because of gravity, at the end of 1 second, it is

about 5 m below the straight line.

### 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.

### Two projectiles are fired from ground level at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. The projectile to hit the ground first will be the one fired at (neglect air resistance)

30 degrees.

### 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 it was at the top of its path.

### A bullet is fired horizontally with an initial velocity of 300 m/s from a tower 20 m high. If air resistance is negligible, the horizontal distance the bullet travels before hitting the ground is about

600 m.

### When an object is partly or wholly immersed in a liquid, it is buoyed up

by a force equal to the weight of liquid displaced.

### The reason a life jacket helps you float is

the density of both you and the jacket together is less than your density alone.

### A rock suspended by a string weighs 5 N out of water and 3 N when submerged. What is the buoyant force on the rock?

2 N

### A block of styrofoam floats on water while a same size block of lead lies submerged in the water. The buoyant force is greatest on the

lead.

### A liter-sized block of ordinary wood floats in water. The amount of water displaced is

less than 1 liter.

### The weight of a 1-squre column of air that extends from sea level to the top of the atmosphere is

101,000 N

### Consider two mercury barometers, one with twice the cross-sectional area of the other. Neglecting capillarity, mercury in the smaller tube will rise

the same height as in the larger tube.

### Alcohol is less dense than water. If alcohol is used to make a barometer on a day when atmospheric pressure is normal, the height of the alcohol column would be

more than 10.3 m.

### When gas in a container is squeezed to half its volume and the temperature remains the same, the gas pressure

doubles.

### It would be easier to pull evacuated Magdeburg hemispheres apart when they are

20 km above the ocean surface.

### Suspend a pair of Ping-Pong balls from two strings so there is a small space between them. If you blow air between the balls, they will swing

toward each other.

### Object A has 6 times the mass and 3 times the volume of object B/. The density of object A is ___________ B's density.

2 times

### The acceleration due to gravity is 16 m/ on a given planet. When a ball is dropped on this planet, what will be its speed at the end of 3 seconds?

48 m/s