Physics 8A
Acceleration & Vectors Worksheet
2) Fill the drawings with sketches of your observations of the bubble for each case.
3) These levels serve as simple accelerometers. They also serve as very simple models of what
happens in your stomach when you plunge down a hill in a roller coaster. Write a brief
description of how the position of the bubble indicates acceleration.
The bubble indicates the direction of the acceleration because the water is pushed back due to the inertial
force. The same thing happens when you drive a car (you act like the water): if you step on the gas, your body will
go backwards, if you hit the brakes, your body will go forwards.
Now try to answer the following questions. Assume that all surfaces are perfectly smooth, i.e. the
cart doesn’t slow down because of friction. For each scenario, describe or make sketches of the
position of the bubble and describe the acceleration of the cart.
4) A cart starts with some initial velocity, (1) travels up an incline until it (2) slows down to a stop,
then (3) rolls back down the incline.
a)
Sketch the location of the bubble for scenarios (1), (2) and (3).
b)
What is the direction of the velocity as the cart travels up the incline?
The only acceleration there is in this situation is the acceleration due to gravity.
So the direction of the
acceleration is vertical, towards the ground. This is true whether the cart is going up or down because the
gravity does not change with the behavior of the cart.
Of course, if you consider the initial push to get the cart moving upwards, then there will be an acceleration
that will be parallel to the incline and directed upwards. At that moment, the bubble will be in the front
of the tube.
c)
How does the direction of the acceleration compare to the direction of the velocity?
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The velocity is parallel to the incline and pointing upwards. Therefore it is not parallel to the acceleration.
The angle between the vectors is
α
π
+
2
if we define
α
as the slope of the incline.
d)
What is the direction of the acceleration as the cart travels back down the incline?
See question b).
e)
How does the direction of the acceleration compare to the direction of the velocity?
The velocity is parallel to the incline and pointing downwards. Therefore it is not parallel to the
acceleration. The angle between the vectors is
α
π

2
if we define
α
as the slope of the incline
5) A cart (1) travels down an incline, (2) rolls along a level surface, and then (3) travels up an
incline.
a)
Sketch the position of the location of the bubble for scenarios (1), (2) and (3).
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 Fall '07
 JACOBSEN
 Acceleration, Work, Velocity

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