All High School Physics Resources
Example Questions
Example Question #3 : Understanding Distance, Velocity, And Acceleration
A box starts at rest and reaches a velocity of after traveling a distance of . What was the acceleration on the box?
The best formula for this will be .
We are given the initial velocity (zero because the box starts at rest), final velocity, and distance. Using these values, we can solve for the acceleration. We are also given the mass, but this is extraneous information.
Divide both sides by .
Example Question #1 : Understanding Distance, Velocity, And Acceleration
A crate slides across a floor. After it has a velocity of . After it has a velocity of . What is the acceleration?
Acceleration is the change in velocity over the change in time:
In this case, even though we look at the crate after different times, the velocity hasn't changed at all.
If there is no change in the velocity, then the acceleration must be equal to zero.
Example Question #4 : Understanding Distance, Velocity, And Acceleration
During a storm, you can usually see the lightning before you hear the thunder, unless you are very close to the lightning strike. What causes this discrepancy?
The speed of light is much faster than the speed of sound
The speed of sound is much faster than the speed of light
We need to know the voltage of the lightning in order to determine the answer
We need to know the current of the lightning in order to determine the answer
There is no definitive scientific reason for this phenomenon
The speed of light is much faster than the speed of sound
Assuming you stand in one place, the distance between you and the lightning strike does not change.
The formula for velocity is:
In this scenario, the distance travelled, , does not change. The time taken to travel this distance, , does change. That means that the velocity must also be changing.
This is an indirect relationship. As increases, will decrease; thus, the object with a greater time of travel (sound) will have a slower velocity.
Example Question #5 : Understanding Distance, Velocity, And Acceleration
A boy jogs down a street in . What was his average velocity?
Velocity is change in displacement over change in time.
We are given the distance traveled and the time period. Using these values, we can find the velocity.
Example Question #1 : Understanding Distance, Velocity, And Acceleration
Which of these is the correct relationship between velocity, distance, and time?
Velocity is defined by a change in distance during a period of time. It is a rate of movement.
The magnitude of velocity is equal to the quotient of the change in distance and the change in time.
Example Question #11 : Understanding Distance, Velocity, And Acceleration
A ball begins to roll with a velocity . If there is no acceleration on the ball, what will its velocity be after ?
We must know the distance traveled to solve
If there is no acceleration on an object, it will have the same velocity regardless of how long it is moving.
Mathematically, we can look at the equation for acceleration.
We know that the acceleration is zero and that the time is ten seconds.
In order for this to be true, the initial and final velocities must be equal.
Example Question #102 : Linear Motion
An athlete kicks a ball into the air. It travels and is in the air for . How fast must the athlete run from the point where he kicks the ball in order to catch it before it lands?
To solve this problem, we need to understand what speed is. Speed is the distance covered in a given amount of time.
In our problem, we need to find the speed of the athlete. We are given the distance the athlete must cover, which is equal to the distance traveled by the ball.
We are also told how much time the athlete has to cover the distance, which is equal to the time the ball is in the air.
Use these values and the equation for speed to find the speed that the athlete must run.
Example Question #101 : Motion And Mechanics
A car is driving at . The driver sees an accident ahead and slows down to . What is the acceleration of the car?
We need to know the time in order to solve
We need to know the time in order to solve
Acceleration is given by the change in velocity over change in time.
While we know the change in velocity, we also need to know the change in time in order to be able to accurately determine the deceleration of the car.
Example Question #109 : Linear Motion
An Olympic sprinter runs a dash in . Assuming he starts at rest, what is his average velocity?
We need to know the acceleration in order to solve.
The average velocity is the total displacement divided by the total time or .
Plug in our given values.
Example Question #101 : Motion And Mechanics
A plane originally travelling north at is informed that a storm is moving into its intended path at a rate of every forty minutes. By how much must the plane increase its velocity in order to outpace the storm?
Our first step is to calculate the velocity of the storm in the proper units.
In order for the plane to move faster than the storm, its velocity must be greater than this value. To find the necessary increase in velocity, we need to subtract the initial velocity from the final velocity.
This is the necessary increase in velocity in order for the plane to match the pace of the storm; thus, our answer must be only slightly greater than . This leads to our answer of .