Name______Acceleration WSdate ____

Show all work (equation used, subs. with units and answer with units) for problems with calculations.

1. Name two possible units for acceleration.Are they fundamental or derived units?

2. A car accelerates from rest to a speed of 31 meters per second in 4.5 seconds. What is the acceleration of the car? Show your work (equation used, substitution of values with units, and answer with correct units.)

3. A truck accelerates from 55 mph to 65 mph in 4.0 s. A sprinter accelerates from rest to 15 mph in 2.0 s. Who has a greater acceleration?

4. A fish is swimming at 0.50 meters per second. Four seconds later, its speed is still 0.50 meters per second. What was its acceleration during the four seconds?

5. Name three ways that a car can change its velocity.

a/

b/

c/

Which of the above 3 ways results in acceleration?

6. A car is moving at 25 m/s when the driver sees a deer and applies the brakes, slowing to a speed of 3.5 m/s in 1.8 s. Find the acceleration of the car.

7. A train moving at a speed of 15 m/s leaves town and accelerates at 3.5 m/s2 for 14 seconds. What is its speed at the end of the 14 seconds?

8. Two cars, A and B, are initially travelling at a speed of 18 meters per second. Car A applies the brakes slowly and comes to a stop in 4.0 seconds. Car B slams the brakes and comes to rest in 2.0 seconds. What is the acceleration of each car?

9. Godzilla is moving at 400 m/s when he collides with Rodan, which causes him to decelerate at 75 m/s2. How long does it take Godzilla to come to rest?

10. Four cars are leaking oil at the same steady rate, so that each leaves marks on the pavement under it as it goes. The patterns, marked A, B C, and D, are shown below. Each car is moving from left to right.

A:

B:

C:

D:

Describe the velocity (dec., inc. or remain same) and the acceleration (neg., pos. or zero) of all four cars.

describe velocitydescribe acceleration

A:

B:

C:

D:

11. Acceleration is defined as a = Δv / t = (vf – vi)/t. The direction of a is the same as the direction of the change in the velocity. If the velocity is increasing (usually to the right or upward), then a is positive. If the velocity is decreasing, then ais negative. In the table below, the vectors show the velocities of one object at two different times, initially and later (final). Find the direction of accelerationa in all 6 cases.

Hint: a has the same direction as the quantity (vf – vi). Notice that vf– vi is the same as vf + (-vi). So, what you have to do is use the head-to-tail method to find the resultant of adding vf to a negative vi. For example, given the following velocities:

vi= and vf =

First draw negative vi as -vi = (It has the same magnitude, but opposite direction as vi.)

Then add vf and –vi head to tail: vf + (-vi) = vf – vi =

Then find the resultant:Since the resultant points to the right, a is to the right.

R

vi vf direction of a vi vf direction of a

1:4:

2:5:

3:6: