PHYS 100 EXAM 1 REPORTED
QUESTIONS WITH COMPLETE
SOLUTIONS
What happens when they are dropped? Compare the speed and acceleration of the
heavy medicine ball with that of the basketball.
A. The speed and acceleration are both the same
B. The speed of the medicine ball is larger, but the accelerations are the same
C. The speed of the basketball is larger, but the accelerations are the same
D. The speed of the balls is the same, but the acceleration of the medicine ball is larger
E. The speed of the balls is the same, but the acceleration of the basketball is larger -
Answer- A. The speed and acceleration are both the same
Is the gravitational force of attraction larger on the heavy medicine ball than it is on the
basketball?
A. The force is equal on the two balls.
B. The force on the medicine ball is larger.
C. The force on the basketball is larger. - Answer- B. The force on the medicine ball is
larger.
Does the heavy medicine ball require a larger force to provide the same acceleration as
the basketball? Justify your answer using one of Newton's Laws of Motion.
A. No; Newton's first law says that because you are not pushing on either ball, they will
have constant motion.
B. No; Newton's second law says that you need the same force to get the same
acceleration.
C. No; Newton's third law says that the forces on the balls are equal and opposite.
D. Yes; Newton's second law says that if something has more mass, you have to push
harder on it to make it move.
E. Yes; Newton's first law says that things with more mass have more inertia. - Answer-
D. Yes; Newton's second law says that if something has more mass, you have to push
harder on it to make it move.
Explain how the heavy medicine ball with greater mass and a greater force of gravity
still has the same motion as a basketball with a lower mass and a lower force of gravity
being dropped from the same height. - Answer- Newton's 2nd law can be used to
explain this problem. There is a greater force pushing on the medicine ball than on the
basketball to make them hit the ground at the same time and accelerate at the same
,time. In other words, because an object with a greater mass (i.e., medicine ball) is
harder to accelerate, the force of gravity must increase to keep the acceleration
balanced between other objects (i.e., basketball).
Click on "Macro Scale." Note the size of the force above the two balls. Predict: If you
double the charge of the blue ball to -8, what will happen to the size of the force on the
balls? (See homework ch 4)
A. It doubles.
B. It increases but doesn't double.
C. It remains the same.
D. It decreases. - Answer- A. It doubles.
Predict: If you double the distance between the blue and red ball, what will happen to
the size of the force on the balls? (See homework ch 4)
A. It doubles.
B. It increases but doesn't double.
C. It remains the same.
D. It decreases, but not by half.
E. It is cut in half. - Answer- D. It decreases, but not by half.
How does the size of the force on the red ball compare to the size of the force on the
blue ball? (See homework ch 4)
A. It depends on the mass I've set on the balls, the larger ball experiences a larger
force.
B. It depends on the mass I've set on the balls, the smaller ball experiences a larger
force.
C. The forces are always the same. - Answer- C. The forces are always the same.
Which law of motion allows you to predict how the force on the red ball compares to the
force on the blue ball?
A. 1
B. 2
C. 3 - Answer- C. 3
What happens if you change the sign of the charge on one of the balls? Predict then
check and correct your answer: what will happen to the sizeof the force if you change
the blue ball from a charge of -4 to +4.
A. It doubles.
B. It increases but doesn't double.
C. It remains the same size.
D. It decreases, but not by half.
,E. It is cut in half. - Answer- C. It remains the same size.
What happens if you change the sign of the charge on one of the balls? Predict and
check: what will happen to the direction of the force if you change the blue ball from a
charge of -4 to +4.
A. It stays the same.
B. It switches. - Answer- B. It switches.
If you scuff across wool carpet wearing rubber shoes, you will shock yourself when you
reach for a metal doorknob, often before you even touch the knob.
What type of charge will have accumulated on your body? How do you know?
A. Negative, I know by looking at the animation. Without that I wouldn't know unless I
looked up what happened when rubber and wool rub together.
B. Negative, when things rub together they always make negative charge because the
electrons have negative charge. - Answer- A. Negative, I know by looking at the
animation. Without that I wouldn't know unless I looked up what happened when rubber
and wool rub together.
When you bring your finger near the doorknob, what happens to the electrons in the
metal?
A. Nothing at all
B. The electrons in the metal move away leaving the part of the door knob closest to me
positive.
C. The electrons in the metal move closer leaving the part of the door knob farthest from
me positive. - Answer- B. The electrons in the metal move away leaving the part of the
door knob closest to me positive.
Explain why, when the metal itself is neutral, a spark will often jump from your finger to
the metal before you touch it. Electrons are attracted to metal. It doesn't matter if it is
neutral or charged.
A. The electrons are repelling each other. When you get close enough to anything,
they'll jump off to get farther away from each other.
B. Metals conduct electricity, so charge will naturally move from your body to the metal.
C. The metal as a whole may be neutral, but the side closest to you is positive and that
attracts the electrons so they jump because they're attracted to the + charges. -
Answer- C. The metal as a whole may be neutral, but the side closest to you is positive
and that attracts the electrons so they jump because they're attracted to the + charges.
When the professor launched the ball while the car was sitting still, analyze its motion.
, What are the forces acting on the ball after it has been shot from the cannon? (pick all
that apply)
A. Downward force of gravity (weight)
B. Upward force from the cannon
C. Friction from the air - Answer- A. Downward force of gravity (weight)
C. Friction from the air
What is the velocity of the ball after it has been shot?
A. Gradually increasing upward velocity followed by a gradually decreasing downward
velocity.
B. Gradually decreasing upward velocity followed by a gradually increasing downward
velocity.
C. Constant upward velocity.
D. Constant downward velocity. - Answer- B. Gradually decreasing upward velocity
followed by a gradually increasing downward velocity.
What is the acceleration of the ball after it has been shot?
A. Gradually increasing upward acceleration followed by a gradually decreasing
downward acceleration.
B. Gradually decreasing upward acceleration followed by a gradually increasing
downward acceleration.
C. Constant upward acceleration.
D. Constant downward acceleration. - Answer- D. Constant downward acceleration.
Now the professor is going to give the cart a little push and launch the ball upward while
the cart is moving at a constant speed. Friction from the air is so small we can ignore it.
Predict what will happen.
A. The ball will land in front of the cart
B. The ball will land in the receptacle just like when it wasn't moving
C. The ball will land behind the cart - Answer- B. The ball will land in the receptacle just
like when it wasn't moving
Now the professor is going to give the cart a little push and launch the ball upward while
the cart is moving at a constant speed. Friction from the air is so small we can ignore it.
What are the forces acting on the ball after it has been shot from the cannon? (pick all
that apply)
A. Downward force of gravity (weight)
B. Upward force from the cannon
C. Sideways force from the push - Answer- A. Downward force of gravity (weight)
QUESTIONS WITH COMPLETE
SOLUTIONS
What happens when they are dropped? Compare the speed and acceleration of the
heavy medicine ball with that of the basketball.
A. The speed and acceleration are both the same
B. The speed of the medicine ball is larger, but the accelerations are the same
C. The speed of the basketball is larger, but the accelerations are the same
D. The speed of the balls is the same, but the acceleration of the medicine ball is larger
E. The speed of the balls is the same, but the acceleration of the basketball is larger -
Answer- A. The speed and acceleration are both the same
Is the gravitational force of attraction larger on the heavy medicine ball than it is on the
basketball?
A. The force is equal on the two balls.
B. The force on the medicine ball is larger.
C. The force on the basketball is larger. - Answer- B. The force on the medicine ball is
larger.
Does the heavy medicine ball require a larger force to provide the same acceleration as
the basketball? Justify your answer using one of Newton's Laws of Motion.
A. No; Newton's first law says that because you are not pushing on either ball, they will
have constant motion.
B. No; Newton's second law says that you need the same force to get the same
acceleration.
C. No; Newton's third law says that the forces on the balls are equal and opposite.
D. Yes; Newton's second law says that if something has more mass, you have to push
harder on it to make it move.
E. Yes; Newton's first law says that things with more mass have more inertia. - Answer-
D. Yes; Newton's second law says that if something has more mass, you have to push
harder on it to make it move.
Explain how the heavy medicine ball with greater mass and a greater force of gravity
still has the same motion as a basketball with a lower mass and a lower force of gravity
being dropped from the same height. - Answer- Newton's 2nd law can be used to
explain this problem. There is a greater force pushing on the medicine ball than on the
basketball to make them hit the ground at the same time and accelerate at the same
,time. In other words, because an object with a greater mass (i.e., medicine ball) is
harder to accelerate, the force of gravity must increase to keep the acceleration
balanced between other objects (i.e., basketball).
Click on "Macro Scale." Note the size of the force above the two balls. Predict: If you
double the charge of the blue ball to -8, what will happen to the size of the force on the
balls? (See homework ch 4)
A. It doubles.
B. It increases but doesn't double.
C. It remains the same.
D. It decreases. - Answer- A. It doubles.
Predict: If you double the distance between the blue and red ball, what will happen to
the size of the force on the balls? (See homework ch 4)
A. It doubles.
B. It increases but doesn't double.
C. It remains the same.
D. It decreases, but not by half.
E. It is cut in half. - Answer- D. It decreases, but not by half.
How does the size of the force on the red ball compare to the size of the force on the
blue ball? (See homework ch 4)
A. It depends on the mass I've set on the balls, the larger ball experiences a larger
force.
B. It depends on the mass I've set on the balls, the smaller ball experiences a larger
force.
C. The forces are always the same. - Answer- C. The forces are always the same.
Which law of motion allows you to predict how the force on the red ball compares to the
force on the blue ball?
A. 1
B. 2
C. 3 - Answer- C. 3
What happens if you change the sign of the charge on one of the balls? Predict then
check and correct your answer: what will happen to the sizeof the force if you change
the blue ball from a charge of -4 to +4.
A. It doubles.
B. It increases but doesn't double.
C. It remains the same size.
D. It decreases, but not by half.
,E. It is cut in half. - Answer- C. It remains the same size.
What happens if you change the sign of the charge on one of the balls? Predict and
check: what will happen to the direction of the force if you change the blue ball from a
charge of -4 to +4.
A. It stays the same.
B. It switches. - Answer- B. It switches.
If you scuff across wool carpet wearing rubber shoes, you will shock yourself when you
reach for a metal doorknob, often before you even touch the knob.
What type of charge will have accumulated on your body? How do you know?
A. Negative, I know by looking at the animation. Without that I wouldn't know unless I
looked up what happened when rubber and wool rub together.
B. Negative, when things rub together they always make negative charge because the
electrons have negative charge. - Answer- A. Negative, I know by looking at the
animation. Without that I wouldn't know unless I looked up what happened when rubber
and wool rub together.
When you bring your finger near the doorknob, what happens to the electrons in the
metal?
A. Nothing at all
B. The electrons in the metal move away leaving the part of the door knob closest to me
positive.
C. The electrons in the metal move closer leaving the part of the door knob farthest from
me positive. - Answer- B. The electrons in the metal move away leaving the part of the
door knob closest to me positive.
Explain why, when the metal itself is neutral, a spark will often jump from your finger to
the metal before you touch it. Electrons are attracted to metal. It doesn't matter if it is
neutral or charged.
A. The electrons are repelling each other. When you get close enough to anything,
they'll jump off to get farther away from each other.
B. Metals conduct electricity, so charge will naturally move from your body to the metal.
C. The metal as a whole may be neutral, but the side closest to you is positive and that
attracts the electrons so they jump because they're attracted to the + charges. -
Answer- C. The metal as a whole may be neutral, but the side closest to you is positive
and that attracts the electrons so they jump because they're attracted to the + charges.
When the professor launched the ball while the car was sitting still, analyze its motion.
, What are the forces acting on the ball after it has been shot from the cannon? (pick all
that apply)
A. Downward force of gravity (weight)
B. Upward force from the cannon
C. Friction from the air - Answer- A. Downward force of gravity (weight)
C. Friction from the air
What is the velocity of the ball after it has been shot?
A. Gradually increasing upward velocity followed by a gradually decreasing downward
velocity.
B. Gradually decreasing upward velocity followed by a gradually increasing downward
velocity.
C. Constant upward velocity.
D. Constant downward velocity. - Answer- B. Gradually decreasing upward velocity
followed by a gradually increasing downward velocity.
What is the acceleration of the ball after it has been shot?
A. Gradually increasing upward acceleration followed by a gradually decreasing
downward acceleration.
B. Gradually decreasing upward acceleration followed by a gradually increasing
downward acceleration.
C. Constant upward acceleration.
D. Constant downward acceleration. - Answer- D. Constant downward acceleration.
Now the professor is going to give the cart a little push and launch the ball upward while
the cart is moving at a constant speed. Friction from the air is so small we can ignore it.
Predict what will happen.
A. The ball will land in front of the cart
B. The ball will land in the receptacle just like when it wasn't moving
C. The ball will land behind the cart - Answer- B. The ball will land in the receptacle just
like when it wasn't moving
Now the professor is going to give the cart a little push and launch the ball upward while
the cart is moving at a constant speed. Friction from the air is so small we can ignore it.
What are the forces acting on the ball after it has been shot from the cannon? (pick all
that apply)
A. Downward force of gravity (weight)
B. Upward force from the cannon
C. Sideways force from the push - Answer- A. Downward force of gravity (weight)
