Coulomb’s Law for Electrical Force

Question 1

10 / 10 pts

1.)    Coulomb’s Law for Electrical Force describes the force between:    a) two masses,    b) two charges,    c) two magnets,    d) a mass and a charge,    e) a mass and a magnet,    d) a charge and a magnet.

a mass and a magnet

 

 

two magnets

 

 

a mass and a charge

 

 

a charge and a magnet

 

 

Correct!

two charges

 

 

two masses

 

 

 

 

 

Question 2

10 / 10 pts

2.)    Both in a normal atom and in the universe as a whole, it is believed that the net charge is:    a) positive,    b) zero,    c) negative.

Correct!

zero

 

 

No answer text provided.

 

 

negative

 

 

positive

 

 

 

 

 

Question 3

10 / 10 pts

3.)    What is a lightning bolt?

Your Answer:

lighting bolt is a n instant eletrical discharge between two point. ia may be between uooer cloud lower clould or between cloud and ground , bascic it is high voltage discharge through lonised air

 

 

 

 

Question 4

10 / 10 pts

4.)    Two North magnetic poles will repel, but two South poles will attract.                        (TRUE/FALSE)

True

 

 

Correct!

False

 

 

 

 

 

Question 5

0 / 10 pts

5.)    A compass placed near a bar magnet will ALWAYS point to a pole.                               (TRUE/FALSE)

You Answered

True

 

 

Correct Answer

False

 

 

 

 

 

Question 6

10 / 10 pts

6.)    Human electrical resistance in case “A” is less than 103 ohms (less than one thousand ohms). In case “B” human resistance is 104 ohms to 106 ohms (ten thousand to one million ohms). In which case, “A” or “B” , is the human wet?

You Answered

in case A

Correct Answers

A

 

 

 

 

 

Question 7

10 / 10 pts

7.)    A magnet produces a magnetic field. What else can generate a magnetic field?

Your Answer:

a moving charge.

 

 

 

 

Question 8

30 / 30 pts

NO HEIC !

8.)    Two positive charges, placed one meter apart, feel a force called F1. The charges are now moved so they are eight meters apart, where they feel a new force called F2. What is the ratio of the new force to the old force? (What is F2/F1 ?)

 

9.)    What is the electrical potential energy of an electron  (charge =  1.602 x 10-19 C),  subject to a potential of 100 kilovolts?

 

10. How much voltage is necessary to drive a3.0 amp current through a 24 ohm resistance?

 

Question 1

10 / 10 pts

1.)    Galileo in his shuttered cabin aboard ship can watch the movements of fish and butterflies, can throw balls or jump in various directions, but he can’t tell from all of this whether he is moving or not. But suppose he could have advanced modern equipment, mechanical, electric, magnetic, optical, or whatever he wanted. Then he would be able to do an experiment to detect if he was moving or not.                                                                                     (TRUE/FALSE)

True

 

 

Correct!

False

 

 

 

 

 

Question 2

0 / 10 pts

2.)    The Ether is the medium for light. Much like a water wave producing ripples in the water, a light wave traveling through outer space is producing ripples in the Ether.                                  (TRUE/FALSE)

You Answered

True

 

 

Correct Answer

False

 

 

 

 

 

Question 3

0 / 10 pts

3.)    A clock flies by you at a relativistic speed. The clock shows that since it first came into sight,  3.9 seconds have gone by. Your clocks show:    a) more than 3.9 seconds have gone by,    b) less than 3.9 seconds have gone by,   c) exactly 3.9 seconds have gone by.

No answer text provided.

 

 

exactly 3.9 seconds have gone by

 

 

Correct Answer

more than 3.9 seconds have gone by

 

 

You Answered

less than 3.9 seconds have gone by

 

 

 

 

 

Question 4

10 / 10 pts

4.)   You are in outer space.  A rocket ship, traveling at a speed of  3/4 c, shoots a light beam at you. The light approaches you at a speed of:    a) 1and 3/4 c,    b) 3/4 c,    c) zero,    d)  c.

1and 3/4 c

 

 

zero

 

 

3/4 c

 

 

Correct!

c

 

 

 

 

 

Question 5

10 / 10 pts

5.)    The time to is called the “proper time”. What does “proper” mean?   (you can answer in one word if you like).

Your Answer:

Time measure by clock having same motion as observer

 

 

 

 

Question 6

10 / 10 pts

6.)    You are in a train car traveling at relativistic speed. Just when another train traveling in the opposite direction is exactly even with you, you see lightning bolts strike both ends of your train car at the exact same moment. The same lightning bolts will strike the other train but an observer in the other train sees that first lightning hit one side of his train car and a few moments later lightning hit the other side. Which observer is right?    a) you are right and the observer in the other train is wrong,    b) the other observer is right and you are wrong,    c) you are both right in your own frames,    d) you are both wrong in your own frames.

Correct!

you are both right in your own frames

 

 

you are both wrong in your own frames

 

 

you are right and the observer in the other train is wrong

 

 

the other observer is right and you are wrong

 

 

 

 

 

Question 7

10 / 10 pts

7.)    “You can’t be older than your mother!” (an old saying)                                (TRUE/FALSE)

Correct Answer

True

 

 

You Answered

False

 

 

 

 

 

Question 8

10 / 10 pts

8.)    A star is  53 Light years away, as measured by an observer on Earth. (The star is not moving relative to Earth.)  You are on a rocket ship traveling from Earth to the star at a relativistic speed. To you, the distance from Earth to t he star looks:    a) longer than 53 Light years,    b) shorter than 53 Light years,    c) exactly 53 Light years.

 

longer than 53 Light years

 

 

exactly 53 Light years

 

 

Correct!

shorter than 53 Light years

 

 

 

 

 

Question 9

10 / 10 pts

9).    Any measurement of this quantity always yields the same number, regardless of the speed of the observer or the speed of the source of the quantity. What is the quantity?

You Answered

Speed of light

Correct Answers

c

 

 

 

 

 

Question 10

10 / 10 pts

10. 10.                Useful information: c = 3.0 x 108m/s

An iron bar of mass  25 kilograms rests on the table in front of you. If all of the mass in the iron bar were converted to pure energy, how much energy would be released?

Question 1

10 / 10 pts

1.)     The force of gravity of the Earth will attract you to the:    a) center of the Earth,    b) surface of the Earth,    c) North pole or South pole, depending on whether you are North or South of the equator,    d) equator.

You Answered

center of the Earth

 

 

Correct Answer

center of the Earth

 

 

North pole or South pole, depending on whether you are North or South of the equator,

 

 

equator

 

 

 

 

 

Question 2

3 / 10 pts

2.)    Does the Earth have a greater gravitational pull on the moon than the moon on earth? (an explanation may help you)

Your Answer:

是的，地球对月球的引力更大，因为它的质量更大。

 

 

 

 

Question 3

10 / 10 pts

3.)    If the mass of the were doubled, your weight would:    a) double,    b) increase by a factor of 4,    c) be cut in half,    d) decrease by a factor of 4.    (you do not have to do a calculation here — just pick the right answer)

be cut in half

 

 

Correct!

double

 

 

increase by a factor of 4

 

 

decrease by a factor of 4

 

 

 

 

 

Question 4

10 / 10 pts

4.)    As you get farther and farther from the Earth, your weight;    a) increases,    b) stays exactly the same,    c) always exactly doubles,    d) decreases.

increases

 

 

Correct!

decreases

 

 

stays exactly the same

 

 

always exactly doubles

 

 

 

 

 

Question 5

10 / 10 pts

5.)    According to the Law of Conservation of Energy, in an isolated system energy will:    a) increase,    b) decrease,    c) stay exactly the same.

increase

 

 

Correct!

stay exactly the same

 

 

decrease

 

 

 

 

 

Question 6

10 / 10 pts

6.)    Does a flying bird have potential energy, and why?

Your Answer:

Yes, because it is above the Earth. Potential energy is the energy due to gravity’s pull on a mass that is some height above the Earth.

 

 

 

 

Question 7

10 / 10 pts

7.)    In an Inelastic collision (not completely elastic):    a) Kinetic energy is conserved,    b) Potential energy is conserved,    c) Energy is not conserved,    d) Some Kinetic energy is converted to Potential energy,  Heat energy,  Sound energy, etc..

Correct!

Some Kinetic energy is converted to Potential energy,  Heat energy,  Sound energy, etc.

 

 

Energy is not conserved

 

 

Potential energy is conserved

 

 

Kinetic energy is conserved

 

 

 

 

 

Question 8

30 / 30 pts

NUMERICAL CALCULATIONS  and  FILE UPLOAD    (NO HEIC!)

8.)    An astronaut is collecting mineral samples on the surface of a small asteroid. The gravity of the asteroid is pulling on the astronaut with a force of 96 Newtons. The astronaut then moves four times further out in space (with all distances being measured from the center of the asteroid). What is the new force of gravity that the asteroid exerts on the astronaut (in Newtons)?

 

9.)    A 60 kg person walks along at a speed of  2m/s. What is the person’s kinetic energy?

 

10.)   A mass of 3 kg falls a certain distance.  You are given that g = 9.8m/s2 ,  and that the final speed of the mass is  10.0 m/s.  (Hint! — turn this last statement into an equation and solve for distance) How far did the mass fall?

Question 1

10 / 10 pts

1.)  Two men are trying to push a wheeled cart in opposite directions. One man is pushing the cart to the right with a force of magnitude 300 N. The other man is pushing the cart to the left with a force of magnitude 350 N. If the positive direction is to the right, what is the net force on the cart? (you don’t have to show a calculation here — just write down the answer)

Correct!

-50N

Correct Answers

-50N

 

 

minus 50 Newtons

 

 

– 50 N

 

 

– 50 Newtons

 

 

-50 N

 

 

 

 

 

Question 2

10 / 10 pts

2.)   Suppose that the universe is infinitely large. An object flies through outer space with a velocity of 359 m/s. If there are no forces on the object, either now or in the future , the object will:    a) continue to fly in the same direction with a speed of 359 m/s, and keep  this up forever,     b) eventually slow down and come to a complete stop,     c) keep going straight, but at a speed which is slower than 359 m/s,     d) eventually accelerate.

eventually accelerate

 

 

eventually slow down and come to a complete stop

 

 

keep going straight, but at a speed which is slower than 359 m/s

 

 

Correct!

continue to fly in the same direction with a speed of 359 m/s, and keep  this up forever,

 

 

 

 

 

Question 3

10 / 10 pts

3.)    A car hits a wall and is brought to a dead stop. The force which the wall exerts on the car is:     a) greater (in magnitude) than the force the car exerts on the wall,      b) less than
the force the car exerts on the wall,     c) exactly the same as the force the car exerts on the wall.

 

 

 

Correct!

exactly the same as the force the car exerts on the wall.

 

 

less than the force the car exerts on the wall

 

 

greater (in magnitude) than the force the car exerts on the wall

 

 

 

 

 

Question 4

3 / 10 pts

4.)    A spy satellite in a circular orbit about Earth is hit by an enemy missile. The satellite does not break up, but something is changed and it falls to Earth. Why was the satellite no longer able to continue in it’s orbit?

You Answered

it was acted on by an external force which caused the change in its motion.

Correct Answers

It wasn’t going fast enough.

 

 

 

 

 

Question 5

10 / 10 pts

5.)    What is a “centripetal” force?   — answer in words,  (a reasonably short sentence) not with an equation, or an “equation in words”

You Answered

Centripetal force is the force that “pulls” an object toward the center of a circular path of motion.

Correct Answers

a force acting toward the center

 

 

 

 

 

Question 6

10 / 10 pts

6.)    Your mass is the same thing as your weight.                                                  (True/False)

True

 

 

Correct!

False

 

 

 

 

 

Question 7

7 / 10 pts

7.   In your own words, state Newton’s 3rd Law (the law of “action” and “reaction”).

(note — not really an “essay” question. Canvas thinks that a long sentence is an essay)

Your Answer:

Newton’s 3rd law says that for every action there is an equal and opposite reaction, which means that for every force there is an equal opposing force acting on the object.

 

 

 

 

Question 8

30 / 30 pts

8. A person kicks a 16 kg ball with a force of 64 N. What is the acceleration of the ball?
9. A 0.25 kg bird flies in a circle with a radius of 8 meters. If the bird’s speed is 8 m/s, what is the bird’s acceleration?

 

10. In problem # 9, what is the force on the bird?

 

Question 1

10 / 10 pts

Acceleration is a vector quantity.

Correct!

True

 

 

False

 

 

 

 

 

Question 2

10 / 10 pts

From the following list, pick the quantity which is not a BASIC quantity. (that is, the quantity you will pick is a compound quantity, built up from the basic quantities):

1. a) distance, b) speed, c) mass,    d) time.

False

 

 

Correct!

True

 

 

 

 

 

Question 3

0 / 10 pts

A motorcycle, starting from rest, accelerates at a constant rate for five seconds. One can say that after three seconds have passed the instantaneous acceleration is exactly equal to the average acceleration.

Correct Answer

True

 

 

You Answered

False

 

 

 

 

 

Question 4

10 / 10 pts

Galileo drops balls from different heights. The balls also have different masses. Some are gold, some are lead, some are copper, etc. . Yet one quantity is constant and is the same for all falls. The quantity is:    a) speed,    b) acceleration,    c) time of fall,    d) distance of fall.

distance of fall

 

 

speed

 

 

Correct!

acceleration

 

 

time of fall

 

 

 

 

 

Question 5

0 / 10 pts

You are watching a 12 kilometer race, and you want to see how many miles this is. You are given that 1.0 km = 0.6214 mi , and you want to make a conversion factor out of this equation. What do you put in the numerator (top), the 1.0 km or the 0.6214 mi ? (Do NOT do the calculation here — just answer the question.)

You Answered

1km

Correct Answers

0.6214mi

 

 

0.6214miles

 

 

0.6214 mi

 

 

0.6214 miles

 

 

 

 

 

Question 6

10 / 10 pts

The formula for average acceleration includes the symbols vf and vi. These symbols represent:     a) average speeds,    b) instantaneous speeds,     c) average accelerations,    d) instantaneous accelerations.

instantaneous accelerations

 

 

average accelerations

 

 

Correct!

instantaneous speeds

 

 

average speeds

 

 

 

 

 

Question 7

10 / 10 pts

There is a difference between velocity and speed. They are not the exact same thing.

Correct!

True

 

 

False

 

 

 

 

 

Question 8

30 / 30 pts

8.)    A bullet shot from a rifle with an average speed of 500 m/s hits a target placed 100 meters away. How long did it take the bullet to travel from rifle to target?

 

9.)     A girl jumps on her bicycle (which is at rest) to try to catch up to her little brother who is riding ahead of her. If she accelerates at the rate of 3.6 m/s2  for four seconds, what will be her final speed at the end of the four second interval?

 

10.)    A squirrel sits on the branch of an oak tree. The squirrel has an acorn and a stopwatch. It wants to know how high up the tree branch is, so it drops the acorn, and using its stopwatch, times the acorn’s fall to the ground to be 1.5  seconds. How high above ground is the squirrel?

 

[ You won’t get any points for answering the following, so you don’t have to answer. But if you have time after the calculations for 8, 9, &10,  your professor would be interested in knowing when was the last time you saw a squirrel with a stopwatch ? ]