Kinematic Variable Relationships

Which variables have a linear relationship with each other? CHOOSE 2 ANSWERS!

• final velocity and time

• initial velocity and time
  

• final velocity and displacement
  

• displacement and time

Which variables have a square relationship with each other? CHOOSE 2 ANSWERS!

• final velocity and time

• initial velocity and time
  

• final velocity and displacement
  

• displacement and time

A ball which is dropped from rest at the top of a building. The ball strikes the ground with a speed of 30 m/s. Assume air resistance can be ignored. This ball is now taken to the top of a different building and dropped from rest again. If the strikes the ground with a speed of twice the original amount for this trial, what change might have occurred to the time of flight, t?

• t

• 1/2t

• 2t

• 1/4t

Starting from rest, object 1 falls freely for 4.0 seconds, and object 2 falls freely for twice as long. Compared to object 1, object 2's height is:

• half as far.

• twice as far.

• three times as far.

• four times as far.

Tags

NGSS.HS-PS2-1

A small car when braking has a constant acceleration. If the car is initially going 20 m/s and must press on the brake a distance of d from the stop sign, how far from the stop sign must the car press on the brake if the car was initially going 3 times greater than the original velocity?

• one third as far.

• three times as far.

• equally as far.

• nine times as far.

Tags

NGSS.HS-PS2-1

Starting from rest, object 1 falls freely from 100 m, and object 2 falls freely from 400 m. Compared to object 1, object 2's time of flight is:

• T

• 2T

• 4T

• 16T

Answer explanation

Since we are going from a known distance to a time, though it is a square relationship, you take the square root of the rate of change.

Car 1 starts with a velocity of 5 m/s, while Car 2 starts with a velocity triple the speed of Car 1. Create a graph that best represents the two car's motion upon pressing on the brakes and experiencing the same acceleration of -1.0 m/s/s. A student considering this situation makes the following prediction: “Car 2 will have triple the stopping distance of Car 1 because it has triple the initial velocity of Car 1.” Is the student correct? Explain your answer.

Answer explanation

Velocity and Displacement have a square relationship so the stopping distance should be 4 times further for the faster car.

Tags

NGSS.HS-PS2-1