## 73 terms

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

add up to equal your weight

###
The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant

velocity is

10N

###
A 300-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the

tree and the bear is

3000N

### A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

zero

###
The synthesis of a large collection of information that contains well-tested and verified hypotheses

about certain aspects of the world is known as a scientific

theory

### An object in mechanical equilibrium is an object

at rest

moving with constant velocity

having no acceleration

###
A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped

from the midpoint of the ceiling and strikes the floor below. The rock hits the floor

exactly below the midpoint of the ceiling

###
A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed

of 400 m/s. It can be stopped by applying a constant force of 20 N for

800 seconds

### A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because the

rifle has much more mass than the bullet

###
Suppose that a tiny gun made of a strong but very light material fires a bullet that is more

massive than the gun itself. For such a weapon

the target would be safer than the shooter

###
Two objects have the same size and shape, but one is much heavier than the other. When

they are dropped simultaneously from a tower, they reach the ground at the same time, but

the heavier one has a greater

momentum

###
To catch a ball, a baseball player extends the hand forward before impact with the ball and

then lets it ride backward in the direction of the ball's motion. Doing this reduces the force

of impact on the player's hand principally because the

time of impact is increased

###
Padded dashboards in cars are safer in an accident than non-padded ones because an occupant

hitting the dash has

increased time of impact

### The force on an apple hitting the ground depends upon

the speed of the apple just before it hits.

the time of impact with the ground.

whether or not the apple bounces.

### A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed?

3m/s

p = mv

p/m= v

v =12/4

= 3m/s

###
A karate expert executes a swift blow and breaks a cement block with her bare hand. The

magnitude of the force experienced by her hand is

identical to the force applied

###
Two billiard balls having the same mass and speed roll toward each other. What is their

combined momentum after they meet?

0

###
When bullets are fired from an airplane in the forward direction, the momentum of the airplane

will be

decreased

###
Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per

second when you are riding the bicycle, then your speed will be

2 m/s

### A broom is easier to balance on its end when the heavier end (the brush end) is

highest, farthest from your hand

### On a balanced seesaw, a boy three times as heavy as his partner sits

1/3 the distance from the fulcrum

###
Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively

make the wrench handle twice as long, you'll multiply the torque by

2

### The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is

above a place of support

###
A 1-kg rock is suspended from the tip of a meter stick at the 0-cm mark so that the meter

stick balances like a seesaw when the fulcrum is at the 25-cm mark. From this information,

what is the mass of the meter stick?

1kg

### Suppose you roll a ball off a tabletop. Will the time to hit the floor depend on the speed of the ball?

No (because the vertical velocity is independent of the horizontal)

### Suppose you roll a ball off a tabletop. Will the time to hit the floor depend on the speed of the ball?

Yes. (because the horizontal component of velocity combined with the vertical component results in a greater speed. That is why the ball travels a longer distance in the same amount of time)

### If you toss a ball vertically upward in a uniformly moving train, it returns to its starting place. Will it do the same if the train is accelerating?

No (since the train is accelerating and the ball is moving at a constant velocity.)

### A park ranger shoots a monkey hanging from a branch of a tree with a tranquilizing dart. The ranger aims directly at the monkey. The monkey lets go of the branch as soon as the ranger shoots. Will the monkey be hit?

yes

### Which planets have a more than one Earth year period, planets nearer or farther from the sun?

planets farther form the sun

### A circularly moving object requires a centripetal force. What supplies this force for satellites that orbit Earth?

gravity

### 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?

it would be the same

### In an accidental explosion, a satellite breaks in half while in circular orbit about Earth. One half is brought momentarily to rest. What is the fate of half brought to rest? What happens to the other half?

the half brought to rest falls to Earth and the other half's velocity doubles

### Science is a body of knowledge that

describes order in nature

is an ongoing activity of humans

condenses knowledge into testable laws

### When you stand at rest on a pair of bathroom scales, the readings on the scales will always

add up to equal your weight

### A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected the force required to keep the puck sliding at constant velocity is

zero

### If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s/s, then its speed reading would increase each second by

20 m/s

### If an object moves with constant acceleration its velocity must

change by the same amount each second

### In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the moon, Earth, or Jupiter

moon

### A 10 kg brick and a 1 kg book are dropped in a vacuum. The force of gravity on the 10 kg brick is

10 times as much

### An astronaut, floating alone in outer space throws a baseball. If the ball floats away at a peed of 20 m /s the astronaut will

move in the opposite direction but at a lower speed

### If a monkey floating in outer space throws hi hat away, the hat and the monkey will both

move away from each other but at different speeds

### A 1 kg glider and a 2 kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at

1/3 m/s

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

divides by 4 the gravitational force between them

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

40 N

### An object is placed exactly halfway between the Earth and the moon. The object will fall toward

Earth

### The amount of gravitational force that acts on the space shuttle while in orbit is

almost as much as the shuttle's weight on the Earth's surface

### 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

5m