Newton's First Law - AP Physics 1
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What net force is required to keep a 500 kg object moving with a constant velocity of 
?
What net force is required to keep a 500 kg object moving with a constant velocity of
Newton's first law states that an object in motion tends to stay in motion unless if acted upon by a net force. This means that if friction is not being accounted for, there is no net force required to keep an object moving if it's in motion. A net force is only required to change an object's motion. The 500 kg object is moving at a constant velocity; therefore, there is no net force (0 Newtons) acting on the object.
Newton's first law states that an object in motion tends to stay in motion unless if acted upon by a net force. This means that if friction is not being accounted for, there is no net force required to keep an object moving if it's in motion. A net force is only required to change an object's motion. The 500 kg object is moving at a constant velocity; therefore, there is no net force (0 Newtons) acting on the object.
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All of the following statements are true. Which of them is NOT explained by Newton's first law of motion?
All of the following statements are true. Which of them is NOT explained by Newton's first law of motion?
Newton's first law of motion refers to objects with no external forces acting on them. Objects with no external forces will maintain the same velocity, meaning that
(1) if they are not moving, they will continue not moving
(2) if they are moving, they will keep moving with the same speed and direction
The answer "Dropping a box causes it to accelerate downwards" refers to a box with a force acting upon it—the force of gravity. Also, the box is accelerating, unlike objects referred to by Newton's first law of motion, which have constant velocities.
Newton's first law of motion refers to objects with no external forces acting on them. Objects with no external forces will maintain the same velocity, meaning that
(1) if they are not moving, they will continue not moving
(2) if they are moving, they will keep moving with the same speed and direction
The answer "Dropping a box causes it to accelerate downwards" refers to a box with a force acting upon it—the force of gravity. Also, the box is accelerating, unlike objects referred to by Newton's first law of motion, which have constant velocities.
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You are traveling on an airplane at constant speed of 650mph. Your friend is traveling in his car at a constant speed of 60mph. Who experiences a larger acceleration?
You are traveling on an airplane at constant speed of 650mph. Your friend is traveling in his car at a constant speed of 60mph. Who experiences a larger acceleration?
Since both you and your friend are traveling at a constant speed, the acceleration of you and your friend is zero. Thus, neither you nor your friend experiences any acceleration. This can be shown mathematically using the equation for acceleration:
Since there is no change in velocity over time acceleration is zero. Also note that when acceleration is zero, so is the net force.
Since both you and your friend are traveling at a constant speed, the acceleration of you and your friend is zero. Thus, neither you nor your friend experiences any acceleration. This can be shown mathematically using the equation for acceleration:
Since there is no change in velocity over time acceleration is zero. Also note that when acceleration is zero, so is the net force.
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You are sitting in a car, at rest, when another car rear ends your vehicle. Why do you and the passengers experience a whiplash, in terms of Newton's laws of motion?
You are sitting in a car, at rest, when another car rear ends your vehicle. Why do you and the passengers experience a whiplash, in terms of Newton's laws of motion?
Because an object at rest tends to stay at rest, when your car is hit your body/neck will 'want' to stay where it was. This will cause your body and neck to 'whip' as it will take time for it to speed up from being hit.
Because an object at rest tends to stay at rest, when your car is hit your body/neck will 'want' to stay where it was. This will cause your body and neck to 'whip' as it will take time for it to speed up from being hit.
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A passenger in an elevator has a mass that exerts a force of 100N downwards. He experiences a normal force upwards from the elevator's floor of 120N. What direction is he accelerating in, if at all, and at what rate?
A passenger in an elevator has a mass that exerts a force of 100N downwards. He experiences a normal force upwards from the elevator's floor of 120N. What direction is he accelerating in, if at all, and at what rate?
The acceleration of the person in the elevator is determined by the net forces and his/her mass. The net force is calculated to be 20N upwards. To find the mass of the passenger, use the following formula:
Then, to find the net acceleration, use Newton's second law.
The acceleration of the person in the elevator is determined by the net forces and his/her mass. The net force is calculated to be 20N upwards. To find the mass of the passenger, use the following formula:
Then, to find the net acceleration, use Newton's second law.
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A 
spaceship travels in the vacuum of space at a constant speed of 
.
Ignoring any gravitational forces, what is the net force on the spaceship?
A
Ignoring any gravitational forces, what is the net force on the spaceship?
In a vacuum, there is no friction due to air resistance. Newton's first law states that an object in motion stays in motion unless acted upon by a net force. Thus the spaceship will travel at the constant speed (zero acceleration) of 
indefinitely and the net force on the spaceship must be zero. This can also be shown mathematically:
In a vacuum, there is no friction due to air resistance. Newton's first law states that an object in motion stays in motion unless acted upon by a net force. Thus the spaceship will travel at the constant speed (zero acceleration) of
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A ball rolls off the back of a train going 
. Neglecting air friction, what is the horizontal speed of the ball just before it hits the ground?
A ball rolls off the back of a train going
Newtons first law states than an object in motion tends to stay in motion unless acted upon by an external force. Because we are disregarding air friction, there is no external force to slow the ball down in the horizontal direction after it falls off the train. The acceleration of gravity would only affect the ball in the vertical direction.
Newtons first law states than an object in motion tends to stay in motion unless acted upon by an external force. Because we are disregarding air friction, there is no external force to slow the ball down in the horizontal direction after it falls off the train. The acceleration of gravity would only affect the ball in the vertical direction.
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A 1675 kilogram car is moving to the right at a constant velocity of 
.
What is the net force exerted on the car?
A 1675 kilogram car is moving to the right at a constant velocity of
What is the net force exerted on the car?
Recall Newton's first law of motion: an object will remain in its state of uniform motion unless acted upon by an external force. The car's motion is described as having a constant velocity which is a uniform state so there are no external forces.
Recall Newton's first law of motion: an object will remain in its state of uniform motion unless acted upon by an external force. The car's motion is described as having a constant velocity which is a uniform state so there are no external forces.
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A spacecraft is deep in space and motionless. Then, the spacecraft separates into two sections going in opposite directions. The first has a mass of 
and is moving with a magnitude of velocity of 
. The second has a mass of 
. Determine the magnitude of velocity of the second section.
A spacecraft is deep in space and motionless. Then, the spacecraft separates into two sections going in opposite directions. The first has a mass of
Use conservation of momentum:
Plug in values.
Solve for 
:
Use conservation of momentum:
Plug in values.
Solve for
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A skydiver of mass 
has reached terminal velocity at 
. Estimate the force of wind resistance she is experiencing.
A skydiver of mass
If the diver has reached terminal velocity, her acceleration is 
.
Thus, according to Newton's second law:
Her net force is equal to zero.
The only forces acting on her are gravity and wind resistance, which must add up to zero.
Where 
is pointing down and thus negative
Plug in values:
Solve for 
If the diver has reached terminal velocity, her acceleration is
Thus, according to Newton's second law:
Her net force is equal to zero.
The only forces acting on her are gravity and wind resistance, which must add up to zero.
Where
Plug in values:
Solve for
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A box is sliding down a plane that has a inclination angle of 
. Calculate the coefficient of kinetic friction 
if the box is moving at a constant velocity 
.
A box is sliding down a plane that has a inclination angle of
If the box is moving at a constant velocity, we know that the sum of the forces acting up and down the inclined plane must add to zero. If the only forces acting are gravity and friction, we can show:
We can gain information about the normal force 
by looking at the forces acting perpendicular to the plane, shown by:
Putting all of this together lets us write the following expression for the forces in acting along the plane, and finally, our answer:
If the box is moving at a constant velocity, we know that the sum of the forces acting up and down the inclined plane must add to zero. If the only forces acting are gravity and friction, we can show:
We can gain information about the normal force
Putting all of this together lets us write the following expression for the forces in acting along the plane, and finally, our answer:
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If an object is being accelerated, what must be true about the forces acting on it?
If an object is being accelerated, what must be true about the forces acting on it?
From the definition of Newton's first law, for an object to not be accelerated, 
. Therefore, for an object to beaccelerated, 
.
From the definition of Newton's first law, for an object to not be accelerated,
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Suppose that two people skydive out of a plane. Person A is 
, while person B is 
. After both people open their parachutes, they begin to slow down until they both reach a constant velocity. How does the net force between persons A and B differ?
Suppose that two people skydive out of a plane. Person A is
For this question, we're told that two skydivers of different masses are jumping out of an airplane. At some point, both skydivers slow down to the point at which they reach constant velocity.
To answer this, we have to realize how constant velocity affects the net force. Since the velocity for both people is constant, that means that no acceleration is occurring. Moreover, because either person is not accelerating, we see that the net force on each person is zero. Consequently, the net force for both person A and B is the same.
For this question, we're told that two skydivers of different masses are jumping out of an airplane. At some point, both skydivers slow down to the point at which they reach constant velocity.
To answer this, we have to realize how constant velocity affects the net force. Since the velocity for both people is constant, that means that no acceleration is occurring. Moreover, because either person is not accelerating, we see that the net force on each person is zero. Consequently, the net force for both person A and B is the same.
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"A box traveling on a slippery surface will continue at its initial speed forever." This statement is consistent with which law?
"A box traveling on a slippery surface will continue at its initial speed forever." This statement is consistent with which law?
The correct answer is "Newton's First Law: every object continues in its state of rest or of uniform velocity in a straight line as long as no net force acts on it." On a slippery surface, we can assume there is no friction. If there is no friction working against the box's movement, the box will continue to move at its initial velocity forever. If the box were on a rough surface, friction from the surface would act against the box, causing the box's velocity to slow and eventually stop (if the force acting on the box is not greater than that of the frictional force).
The correct answer is "Newton's First Law: every object continues in its state of rest or of uniform velocity in a straight line as long as no net force acts on it." On a slippery surface, we can assume there is no friction. If there is no friction working against the box's movement, the box will continue to move at its initial velocity forever. If the box were on a rough surface, friction from the surface would act against the box, causing the box's velocity to slow and eventually stop (if the force acting on the box is not greater than that of the frictional force).
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An object rests in the middle of an empty, motionless boxcar on a perfectly frictionless surface.
What will happen when the boxcar is pulled forward by a locomotive?
An object rests in the middle of an empty, motionless boxcar on a perfectly frictionless surface.
What will happen when the boxcar is pulled forward by a locomotive?
According to Newton's first law, an object will remain at rest until a force is applied. If the floor of the boxcar is perfectly motionless, than the object will remain in the same spot in relation to the earth. This will make it appear to move to the back of the boxcar.
According to Newton's first law, an object will remain at rest until a force is applied. If the floor of the boxcar is perfectly motionless, than the object will remain in the same spot in relation to the earth. This will make it appear to move to the back of the boxcar.
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How much force must be applied to keep an object with a mass of 
moving to the left at a constant velocity of 
?
How much force must be applied to keep an object with a mass of
Force is defined as
Since the velocity is constant, the acceleration is zero. Therefore the force required to keep this object in motion is zero.
This is also stated in Newton's First Law: "An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force."
Force is defined as
Since the velocity is constant, the acceleration is zero. Therefore the force required to keep this object in motion is zero.
This is also stated in Newton's First Law: "An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force."
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A van is driving around with a bowling ball in the back, free to roll around. The van approaches a red light and must decelerate to come to a complete stop. As the van is slowing down, which direction is the bowling ball rolling?
A van is driving around with a bowling ball in the back, free to roll around. The van approaches a red light and must decelerate to come to a complete stop. As the van is slowing down, which direction is the bowling ball rolling?
According to Newton's First Law of Motion, an object that is in motion will stay in motion unless acted on by another force. When the van slows down, the ball will want to continue moving forward, and the friction between it and the floor of the van is not strong enough to keep the ball back.
According to Newton's First Law of Motion, an object that is in motion will stay in motion unless acted on by another force. When the van slows down, the ball will want to continue moving forward, and the friction between it and the floor of the van is not strong enough to keep the ball back.
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A van with helium-filled party balloons is driving around when it approaches a red light. When the van is slowing down to come to a complete stop, in which direction do the balloons go?
A van with helium-filled party balloons is driving around when it approaches a red light. When the van is slowing down to come to a complete stop, in which direction do the balloons go?
According to Newton's First Law of Motion, something in motion will stay in motion unless acted on by another force. As the van slows down, we expect free object in the van to continue moving forward within the van. However, helium is lighter than air so the air in the van will continue to move forward, leaving the light balloons in the back of the van.
According to Newton's First Law of Motion, something in motion will stay in motion unless acted on by another force. As the van slows down, we expect free object in the van to continue moving forward within the van. However, helium is lighter than air so the air in the van will continue to move forward, leaving the light balloons in the back of the van.
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