### objects that have zero acceleration

objects moving at constant velocity, at rest, and in mechanical equilibrium

### hang from a pair of gym rings and the upward support forces of the rings will always

add up to equal your weight

### if a freely falling object were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be

greater than the second before

### a player hits a ball with a bat. the action force is the impact of the bat against the ball. the action to this force is the

force of the ball against the bat

### which of the following has the largest momentum relative to earth

the pickup truck speeding along the highway

### for the astronauts inside the orbiting space shuttle, there is no force of earth's gravity acting on them. this statement is

always false

### a rock is thrown upward at 50e with respect to the horizontal. as it rises, its vertical component of velocity

decreases

### the impulse-momentum relationship and example

impulse is equal to the change in momentum. when a golfer is about to hit the ball, zero force is exerted until contact. when contact arrives, there is an increase in momentum due to the impulse

### newton's first law of motion

every object continues in a state of rest or of uniform speed in a straight line unless acted upon by a nonzero force. inertia

### newton's second law of motion

the acceleration produced by net force is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object. force of hand accelerates brick

### newton's third law of motion

whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. earth pulls on ball and ball pulls on earth

### difference between velocity and acceleration

velocity is speed and direction of the object and acceleration is moving things that undergo variations in motion

### an object is pulled northward with a force of 10 N and southward with a force of 15 N. The magnitude of the net force on the object is

5 N

### if a nonrotating object has no acceleration, then we can say for certain that it is

in mechanical equilibrium

### whirl a rock at the end of a string and it follows a circular path. string breaks, the tendency of the rock is to

follow a straight-line path

### an object is propelled along a straight-line path by a force. if the net force were doubled, its acceleration would

double

### an object is in free-fall. at one instant, it travels at a speed of 50 m/s. exactly 1s later, its speed is about

60 m/s

### an archer shoots an arrow. consider the action force to be the bowstring against the arrow. the reaction to this force is the

arrow's push against the bowstring

### a freight train rolls along a track with considerable momentum. if it rolls at the same speed but has twice as much mass, its momentum

doubled

### a cannon recoils from firing a cannonball. the speed of the cannon's recoil is small because the

cannon has more mass than the ball

### if your mass, the mass of the earth, and the mass of everything in the solar system were twice as much as it is now, yet everything stayed the same size, your weight on earth would

quadruple

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

remains unchanged

### galileo's concept of inertia

the name given to the property by which objects resist which objects resist changes in motion is friction

### the direction of friction compares with the velocity of a sliding object because

when you push hard enough on sliding furniture to match the friction, the net force is zero and it slides at constant velocity

### is velocity is a vector? is speed?

velocity is a vector and speed is not because constant velocity means constant speed and constant direction. constant speed merely means steady speed. vector quantities specify direction and magnitudes and velocity does this, not speed

### EF=0

equilibrium rule. E "the vector sum of." F stands for forces. vector quantities are equal to zero

### law of conservation of momentum

in the absence of an external force, the momentum of a system remains unchanged

### elastic collision

when a ball moves and hits another ball and then it stops while the other ball begins to move

### law of conservation of energy

energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes

### inverse square law

intensity of an effect from a localized source spreads uniformly throughout the surrounding space and weakens with the inverse square of the distance

### archimedes' principle

an immersed body is buoyed up by a force equal to the weight of the fluid it displaces

### pascal's principle

a change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid