AP Physics 1 : Fundamentals of Displacement, Velocity, and Acceleration

Study concepts, example questions & explanations for AP Physics 1

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Example Questions

Example Question #291 : Linear Motion And Momentum

A man walks  meters east and  meters north. What is the difference between his distance and displacement?

Possible Answers:

Correct answer:

Explanation:

Displacement is the difference from the person's initial position and final position. In this problem, since the man is walking on orthogonal axes (x and y), we determine his displacement by using the pythagorean theorem. 

 

Distance travelled is the sum of all motion, which is:

The difference between distance and displacement is:

Example Question #21 : Fundamentals Of Displacement, Velocity, And Acceleration

Determine the displacement of an object that moves  east and  northeast afterwards?

Possible Answers:

Correct answer:

Explanation:

Measuring the total displacement means finding the norm of the vector that starts from the original spot to the final.

Since the object moved 2 feet east and 1 feet north , the norm of this vector can be found by doing:

Example Question #293 : Linear Motion And Momentum

Which of the following graphs displays a particle with constant velocity?

Possible Answers:

Vt physics 10 29 question 2 incorrect answer 3

Vt physics 10 29 question 2 correct answer

Vt physics 10 29 question 2 inorrect answer 2

Vt physics 10 29 question 2 incorrect answer 4

Correct answer:

Vt physics 10 29 question 2 correct answer

Explanation:

For this question, we need to find out which graph represents constant velocity.

First, let's recall that velocity is defined as the amount of displacement that an object undergoes in a given amount of time. Hence, a graph in which the displacement is changing at a constant rate is showing a velocity that is constant. If this line is not straight in a graph of displacement vs. time, then the velocity is changing during the object's travel.

In a graph of acceleration vs. time, a straight flat line indicates that acceleration is not changing. And since acceleration is defined as a change in velocity with respect to time, a flat line indicates that the velocity is changing at a constant rate. Thus, in this scenario, velocity would not be constant (since it is changing at a constant rate). In an acceleration vs. time graph that contains an upward facing straight line, this indicates that the acceleration is increasing at a constant rate. And if acceleration is increasing at a constant rate, then the velocity would be increasing at an even greater rate (an exponential rate).

Example Question #294 : Linear Motion And Momentum

Consider the following scenario:

Sledder

A sledder of mass  is at the stop of a sledding hill at height  with a slope of angle .

If , and the friction between the sledder and snow is , at what rate does the sledder accelerate down the hill? Neglect air resistance.

Possible Answers:

Correct answer:

Explanation:

We will use Newton's 2nd law to solve this problem:

There are two forces acting on the sledder in the direction of their motion: friction and gravity. We are given the frictional force, so we just need to calculate the component of gravity in the direction of the sledder. We will start with the force of gravity:

And then to get the component in the direction of the sledder's motion, we will use the sin function:

If you're wondering why we use sine, think about the situation practically. As the angle grows, the hill gets steeper, and their will be more gravitational force in the direction of motion. Hence, we use sine. Now adding these forces together to get the net force:

We subtracted the friction force since it is always in the opposite direction of motion.

Now solving for acceleration:

Example Question #21 : Fundamentals Of Displacement, Velocity, And Acceleration

Consider the following system:

Frictionless pully

Two masses, A and B, are attached to the end of a rope that runs through a frictionless pulley.

The system is initially rest. At time , the system begins to move. After mass A has traveled , what is its velocity?

Possible Answers:

Correct answer:

Explanation:

First, we need to determine the rate at which the masses accelerate. We will start with Newton's 2nd law:

There are two forces acting on the system: gravity on each mass. For simplicity sake, we will examine these forces with respect to mass. Therefore, the force on mass B becomes an upward tension force on mass A. Now we need to clarify which direction is positive. For this problem, we'll say that a downward force is positive, and an upward force is negative.

We'll start with the gravitational force:

Now for tension. The tension force is simply the gravitational force applied to mass B:

Note that it's negative because it is in the upward direction

Now adding these together to get the net force:

Substituting this back into the original equation, we get:

Where m is the combination of both masses:

Rearrange for acceleration:

Now we can use a kinematics equation:

We are told that the system is initially at rest, so we can eliminate that term:

Rearranging for time, we get:

We know these values, so we can solve for time:

Now we can solve for final velocity using:

Example Question #572 : Ap Physics 1

An an archer has shot an arrow at an angle of  above the horizontal with an initial velocity of . How far has the arrow traveled horizontally by the time it reaches its highest point? Neglect air resistance.

Possible Answers:

Correct answer:

Explanation:

The arrow will have a vertical velocity of 0 when it reaches it's high point. Therefore, we can use the initial vertical velocity to calculate how long it takes to get there:

Then using the follow expression to determine time:

We can then multiply this time by the horizontal component of the arrow's velocity, which is constant since we are neglecting air resistance:

Plug this value into the distance formula to find the range.

Example Question #291 : Linear Motion And Momentum

An archer is riding a horse that is galloping at a rate of  to the north. If the archer shoots an arrow directly east at an angle of above the horizontal and with a velocity of , what is the velocity of the arrow relative to the ground?

Possible Answers:

Correct answer:

Explanation:

To calculate the arrow's velocity relative to the ground, we will need to combine the velocity of the archer and the velocity of the arrow relative to the archer. To do this, we will first need to split the velocity of the arrow relative to the archer into it's vertical and horizontal components:

Then we can combine the two horizontal velocities (archer and arrow relative to archer). However, it should be noted that these two velocities are at right angles to each other (north and east), so we will need to use Pythagorean's theorem to combine them:

Now we can combine our total horizontal velocity with the vertical velocity to get our total velocity:

Example Question #574 : Ap Physics 1

Two cars are racing side by side on a perfectly circular race track. The inner car is from the center of the track. The outer car is from center of the track.

If the outer car accelerates from to , determine the angular acceleration.

Possible Answers:

None of these

Correct answer:

Explanation:

Example Question #575 : Ap Physics 1

A police officer sees a car in a  zone approaching a stop sign.  The driver doesn't see the sign until the last minute and then slams on his breaks, decelerating at a constant rate to a stop just before the sign, but leaves a skid mark  long.  Reviewing the dash-cam tape, the officer is able to tell that the car took  to stop.  Was the driver speeding?  Assume the wheels locked when the brakes were applied.

Possible Answers:

No, the car was traveling approximately 

No, the car was traveling approximately 

Yes, the car was traveling approximately 

No, the car was traveling approximately 

Yes, the car was traveling approximately

Correct answer:

Yes, the car was traveling approximately 

Explanation:

To find how fast the driver was going before applying the brakes, we use the following kinematics formula since acceleration is constant:

Where  is the displacement,  is the initial velocity (before applying the brakes),  is the final velocity (which is zero since the car came to a stop), and  is time. We can now plug in the known values into the above equation and solve for the initial velocity:

In order to know if the driver was speeding, we must convert this speed and/or the speed limit in the same units. Let's put this speed in kilometers per hour.

As we can see, the driver was exceeding the  speed limit and was thus speeding.

Example Question #21 : Fundamentals Of Displacement, Velocity, And Acceleration

A submarine launches a missile from underwater. The missile passes through the surface of the sea at a velocity of . At this point, a thruster ignites, causing the missile to accelerate in a straight line at . After 10 seconds of acceleration, how far has the missile traveled?

Possible Answers:

Correct answer:

Explanation:

We need our kinematic equation that relates displacement, initial velocity, and acceleration:

We can neglect gravity in this problem since the statement says that the missile accelerates in a straight line at a constant rate.

Plugging in our values, we get:

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