PHYS 1415 exam 2

which of these has the greater density?

1 gram of lead

how much power is expended if you lift a 100-N rock 5 meters in 2 seconds?

250 W

You have kinetic energy when you run. If you run 3 times as fast, you'll have a kinetic energy

3 times as much

A baloon hovering best illustrates

Archimede's principle

Above the earth's atmosphere, Earth gravity is zero or nearzero

False

Impluses are smaller when bouncing occurs

False

Padding is put in the dashboard of a car to reduce momentum during a collision,

False

The density of matter is given by its mass multiplied by its volume

False

The gravitational field of earth is very weak up there in space shuttle territory

False

Water expandswhen heated from 0 C to 4 C

False

When a fluid gains speed, the pressure within the fluid increases

False

Work is equal to the applied force x time the force acts

False

the total amount of all energies in a substance is its temperature

False

If your speeding car slams into a haystack and comes to rest, how will the force that acts on it compare with slamming into a brick wall and coming to rest?

Less

If your speeding car slams into a haystack and comes to rest, how will the IMPULSE that acts on it compare with slamming into a brick wall and coming to rest?

Same

Superman is at rest in free space and thows an asteroid that has more mass than superman, then which moves faster?

Superman

Which has more momentum, a 100-kg linemen running at 10km/hr or a 75-kg quarterback running at 12 km/hr

The lineman

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

True

An earth satalite is a projectile that falls around the Earth instead of falling into it

True

For every object, hot or cold, both absorbs and emits radiant energy

True

Gravitation on your body by the earth is less at the top of a mountain

True

Heat is the energy that transfers from one object to another because of a temperature difference.

True

Potential energy and kinetic energy are two forms of mechanical energy

True

Pressure in a liquid depends on the density and its depth

True

The bouyant force acting on a floating object is equal to both the weight of the object and the weight of the fluid displaced

True

The earth pulls harder on the moon than the moon pulls on the earth

True

The rate at which work is done is called power

True

There is a lower limit to how cold something can be

True

When work is done on a system, the energy of the system changes

True

Earth satellites are typically more than 100 km high so as to be above the Earth's

atmosphere

a barometer measures

atmospheric pressure

which has more potential energy, a 50-kg load 2 meters high, or a 100-kg load 1 meter high?

both the same

Thermal energy travels from one part of a body of water to another primarily by the process of

convection

To slightly increase the volume of some 4 C water, you should

cool it or heat it

When you squeeze and compress a water baloon, you also

decrease its volume, and increase internal air pressure

When you fire a projectile horizontally while falling below the line of sight is

depends on the initial speed

Water pressure at the bottom of the ocean depends on

depth and density of salt water

If the mass of the earth some how doubled, and everything else remained the same, my weight ould

double

The satellite that undergoes changes in its speed is the satellite in

eliptical orbit

What a hydraulic device cannot multiply

energy

Impulse and Momentum are 2 words for the same concept

false

The source of geothermal energy is solar origin

false

An object that has kinetic energy must have

force

A glass vase that falls on the floor will be less likely to break if the floor is carpeted . This is because the

force of the impact will be less because time of impact will be longer

When Nellie Newton pushes an object with twice the force for twice the distance, the work she does on the object is

four times as much

Consider the gravitational force between Earth and a meteor in outer space. If the meteor moves so its distance from the Earth's center doubles, the gravitational force on the meteor will be

half

A moving freight car collides with an identical car at rest on the track. The collision is elastic. compared with the speed of the first car befoe the collision, the speed of the combined cars is

half as much.

If you stood atop a ladder on earth that was as tall as the earth's radius, so you were twice as far from the earth's center your weight atop the ladder would be

half its normal value

Fur keeps an animal warm in the winter, because t

he fur contains trapped air

Consider molecules of hydrogen gas and molecules of heavieroxygen gas that have the same kinetic energy. The molecules with more speed are

hydrogen

A cannonball shot from a cannon with a long barrel will be faster because the cannonball recieves greater

impulse

Strictly speaking, when the lights are turned on in an automobile

more gasoline is eventually consumed

Skellly the skater travels at a high speed and needs a certain amount of force to stop him. More stopping force will be needed if he has

more, momentum, mass and less stopping distance

Kinetic energy is the energy an object has due to its

motion

Pull one end of an ideal pulley system down 1 meter with a 100 N force , and you'll lift a 20-N load a distance of

none of these

What force prevents a stallite from fallling?

none of these-?

Heat energy travels from the sun to the earth by the process of

radiation

When water changes phase from vapor to liquid, energy is

released by the vapor

While a rock tossed in the water sinks, the bouyant force on it

remains constant.

The difference between a cup of hot chocolate, and a cup of cooled chocolate has to do with the difference in molecular

speeds

The bouyant force that acts on a boat floating in water is equal to the weight of

the boat and the water displaced by the bot.

Archimedes' Principle

the buoyant force on an object is equal to the weight of the fluid displaced by the object

Which is greater, the gravittional force between the earth and the moon, or between the earth and the sun?

the earth and the moon

When work is done on an object, the energy gained by the object is equal to

the force and distance moved by the object

The fact that bouyant force act upward on fish in water is due to

the greater upward and less downward water pressure on the fish

A tennis ball is launched from a launching machine. Compared with the amount of impulse on each ball, the amount of of impulse on the machine is

the same.

Which will warm up faster on a sunny day, the water in a puddle or the sand that surrounds the puddle?

the sand

When a net force acts on a system, the momentum of a system will change

true

When the net force on a system is zero, no change in the system's momentum occurs

true

The brakes are slammed on a speeding truck and it skids to a stop. If the truck were heavily loaded so it had twice the total mass, the skidding distance would be

twice as far

If you could throw abaseball horizontally, at a speed of 8 km/s with no air drag and nothing to stop it,

wait 90 minutes and it will return to you

Consider a ring with a gap in it, when the ring is heated, the gap becomes

wider

Firewalker who walk barefoot on red-hot wooden coals depend on

woods poor conductivity

You float higher in salt water because in salt water

you don't have to immerse as deep to displace your weight.