Physics final exam concept questions

A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket?

0 J bc the bucket does not move form the initial spot

Two point charges, initially 2 cm apart, are moved to a distance of 10 cm apart. By what factor does the resulting electric force between them change?

1/2s

Three resistors with values of 4 ohms, 6 ohms, and 10 ohms are connected in parallel. What is their equivalent resistance?

1/4+1/6+1/10 = .25+.17+.1

If the batteries in a portable CD player provide a terminal voltage of 12 V, what is the potential difference across the entire CD player?

12V

Three resistors with values of 4 ohms, 8 ohms, and 6 ohms, respectively are connected in series. What is their equivalent resistance?

18 ohms

Three resistors with values of 3 ohms, 6 ohms, and 12 ohms are connected in series. What is the equivalent resistance of this combination?

21 ohms

A person playing twister has both hands and one foot on the playing surface. How many points make up the person's area of support?

3

Ball A has triple the mass and speed of ball B. What is the ratio of the kinetic energy of ball A to ball B.

3x(3)^3=27

If the potential difference across a pair of batteries used to power a flashlight is 6.0 V, what is the potential difference across the flashlight bulb?

6 V

If the charge is tripled for two identical charges maintained at a constant separation, the electric force between them will be changed by what factor?

9 (3x3) (q1)(q2)

If a 9.0 V battery is connected to a lightbulb, what is the potential difference across the bulb?

9 V

If the potential difference across the bulb in a camping lantern is 9.0 V, what is the potential difference across the battery used to power it?

9 V

Which of the following is an example of a significant change in momentum

A tennis ball getting hit into a net

What is the term for the net force directed toward a center of an object's circular path?

Centripetal force

What safety devices prevent electrical fires?

Circuit Breakers and fuses

define work in a scientific sense of the word

Force applied to an object moving in the same direction as objects in motion

For physics work to be done, what has to happen?

Force must be parallel to direction of force

How is frequency and pitch related?

Frequency go up pitch goes up, frequency goes down pitch goes down.

Three resistors connected in series carry currents labeled I1, I2, and I3, respectively. Which of the following expresses the total current, It, in the system made up of the three resistors in series?

I= I1=I2=I3

How is current affected if the time interval over which the charge passes through a given area decreases while the amount of charge remains the same?

I=q/t t decreases so current increases

Where us the center of mass in a billiard ball?

In the center of the ball

A bill is whirled on a string until the string breaks. What causes the ball to move off in a straight line?

Inertia

How are frequency and period related?

Inverses of each other

A 20 kg shopping cart moving at a velocity of 0.5 m/s collides with a store wall and stops. What happens to the momentum of the cart?

It decreases

What is happening when a glass rod becomes positively charged?

It is losing electrons

A person sitting in a chair stands up causing the chair to roll backwards across the floor. Describe the momentum of the chair?

It was 0 until the person got up

The Hubble Space telescope is orbiting the earth at 7500 m/s. What would happen if it began to slow down?

It will crash into earth

Is power a rate unit?

J/s

A 9V battery supplies 9___ of energy per coulomb

Joules

If friction is the only force acting on an object during a given physical process, what is happening to the kinetic energy during this time?

KE is decreasing bc it is slowing down

Describe the energy forms involved in hitting a tennis ball?

Kinetic Potential Energy

A rubber ball moving at a speed of 5 m/s hit a flat wall and returned to the thrower at 5 m/s. The magnitude of the momentum of the rubber ball

Magnitude is the same

Define Net work

Net force X the distance applied

A child moving at a constant velocity carries a 2 N ice cream cone 1 m across a level surface. What is the net work done on the ice cream cone?

No work done force is perpendicular to cone

Describe speed of solid, liquid and gas?

Solid-fast, gas- slowest, and liquid- middle

Define negative stability?

The center of gravity is moved lower after any displacement of the object

When work is negative, what is happening?

The force applied is opposite of the motion

If a wave with positive displacement over equilibrium meets a wave with negative displacement over equilibrium, what happens?

They cancel out

How do charges move in insulators?

They don't

True or False: The impulse experienced by a body is equivalent to the body's change in momentum?

True

What is a common formula for work?

W=Fd

List the units for power?

Watts, kilowatts, horsepower.

Which of the following wires would have the least resistance?

a copper wire 5 cm in length and 10 degree C

What variable effects electrical forces?

change and distance apart

What material most easily transports charge?

conductors (metals)

What happens when a rubber rod is rubbed on a piece of fur, giving it a negative charge?

electrons transfer from fur to the rubber rod

Ture or false- Work is done if the displacement is not zero.

false

Friction converts some of the mechanical energy into _____ energy.

heat

The force of a hammer hitting a nail multiplied by the time of contact between the hammer and nail is called what?

impulse

The process of charging a conductor by bringing it near another charged object and then grounding the conductor is called?

induction

A team of crime scene investigators is analyzing a bullet imbedded in a portion of a steel door. What type of collision occurred between a the bullet and door?

inelastic

When does a fired bullet begin to drop?

just as it exits the barrel

What are the SI units for momentum?

kg m/s

What is defined as energy in motion?

kinetic energy

Describe electrical conductors

metallic, allows electrons to travel across surfaces.

A roller coaster climbs up a hill at 4 m/s and then zips down the hill at 30 m/s. Describe the momentum of the roller coaster?

momentum is greater down the hill

Two skaters are pushing each other away. One skater's mass is 60 kg and the other skater's mass is 72 kg. If the skaters push away from each other without spinning

momentum would be equal but opposite

Does the luster of a metal affect resistance?

no

Define repelling force?

occurs between charges that are the same

Define attractive force

occurs when opposite charges are near

The resistance in a circuit is measured in which units?

ohms

A circuit has a continuous path through which charge can flow from a voltage source to a device that uses electrical energy. What is the name of this type of circuit?

seris

Define potential energy?

stored energy of an object

List types of centripetal force

tension, friction, centripetal force

Describe the Doppler effect

the apparent change in frequency due to the motion of the source (or receiver)

Two vehicles of the same mass are making left turns, but one is making a tighter turn with a smaller radius. Which vehicle will require a greater centripetal force to make the turn.

the one with the smaller radius

How does the potential difference across the bulb in a flashlight compare with the terminal voltage of the batteries used to power the flashlight?

they are the same

When someone bends to touch their toes why does the lower body extend backwards?

to keep center of mass above area of support

when an object is moving with uniform circular motion, which way is the centripetal acceleration directed?

towards the center

True or False: The change in an object's momentum is equal to the product of the force applied to the object and the time interval

true

Two identical meteors (equal mass) are traveling in outer space. Meteor A is moving at 9000 m/s and meteor B is moving at 4500 m/s. How much more momentum does meteor A have than meteor B?

twice as much

Describe the variables that affect a wire's resistance?

type of wire, temperature, diameter, and length

Does the centripetal force point in the same direction as the centripetal acceleration?

yes

Is electric charge conserved?

yes

Two swimmers relax close together on air mattresses in a pool. One swimmer's mass is 48 kg, and the other's mass is 55 kg. If the swimmers push away from each other, is their momentum equal and opposite?

yes

Do molecules that are hotter have greater kinetic energy?

yes higher velocity

Do all masses pull on other masses?

yes, law of universal gravitation