**Interactive Lecture Demonstrations (ILDs)
for Physics
**

**Work your way down this page watching
the linked videos and
when asked to perform a task refer to the relevant handout. There are many
Notes:
I have added to each section as you
go down this page. I have tried to explain anything I think you may find
difficult please read these as you go and if you still have trouble ask your
classmates or raise your hand and ask for help.**

**Kinematics 1 - Human Motion**

Watch
K1D1GIntro.mov to get a general introduction to the activities that follow.
**Note:**
In the following demonstrations use one colour pen to make predictions and
another colour to record your observations. Make it clear using a key which
colour is which. Don't rub anything out. Even if your predictions don't match
the observations it is useful to compare the two and see why you needed to
modify what you thought. It is also a great idea to discuss your predictions and
subsequent observations with your classmates so I encourage you to do this as
you go to help you understand what is going on. If you need any help as you go
please raise your hand.

**Demonstration 1A**

Watch K1D1Intro.mov and record your prediction on sheet 1.

Watch
K1D1_results.swf and check your prediction. Alter your graph if necessary to
fit your observations. **
Note:**
Professor Thornton highlights a section of the graph illustrating that we are
interested in the linear (straight) section of the graph which is uniform motion
(at a constant speed). Remember as you work through the following demonstrations
that we only concerned with uniform motion (and later uniform acceleration)
which are the straight line (linear) sections of the graphs shown. In practice
this is hard to do in many of the demonstrations so you will have to remember
that many of the curved sections of the graphs are due to Professor Thornton
speeding up and slowing down at the start and end of his motion.

Watch
K1D1_interp.swf and make notes on your sheet if necessary following this
video. **Note:**
It is important that you understand that distances, velocities and accelerations
to the right are given positive values and to the left are given negative
values. This is called a convention.

**Demonstration 1B**

Watch K1D1AIntro.mov and record your prediction on sheet 1.

Watch
K1D1A_results.swf and check your prediction. Alter your graph if necessary
to fit your observations. **
Note:**
Once again it is important to concentrate on the section of the graph that
Professor Thornton highlights which is linear i.e. uniform motion.

Watch
K1D1A_interp.swf and make notes on your sheet if necessary following this
video. **Note:**
Moving away from the detector is motion in the positive direction (right) and
moving towards the detector is motion in the negative direction (left).

**Demonstration 2A**

Watch
K1D2Intro.mov and record your prediction on sheet 1.
**Note:**
Velocity to the right (moving away from the motion detector) is positive and to
the left (moving towards the detector) is negative.

Watch K1D2_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K1D2_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 2B**

Watch K1D2AIntro.mov and record your prediction on sheet 1.

Watch K1D2A_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K1D2A_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 3**

Watch
K1D3Intro.mov and record your prediction on sheet 1.
**Note:**
Your predictions should be relative to the motion seen in earlier
demonstrations. Think about what will change.

Watch
K1D3_results.swf and check your prediction. Alter your graph if necessary to
fit your observations. **
Note:** Both the slope and
the height of the graphs over time will be affected. Remember the connection
between the slope of a distance time graph and the velocity of an object?

Watch
K1D3_interp.swf and make notes on your sheet if necessary following this
video. **Note:**
Your predictions should be relative to the motion seen in earlier
demonstrations. What will change? The slope and / or the height?

**Demonstration 4**

Watch K1D4Intro.mov and record your prediction on sheet 1.

Watch K1D4_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K1D4_interp.swf and make notes on your sheet if necessary following this video.

**Kinematics 2 - Motion with
Carts**

**>>> Warning the sound is
much louder in some of these videos <<<**

**Demonstration 1**

Watch K2D1Intro.mov and record your prediction on sheet 2.

Watch K2D1_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K2D1_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 2**

Watch K2D2Intro.mov and record your prediction on sheet 2.

Watch K2D2_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K2D2_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 3**

Watch
K2D3Intro.mov and record your prediction on sheet 2.
**Note:**
Recall the definition of acceleration and how it is related to velocity. A small
fan is placed on top of the frictionless cart in this demonstration to provide a
constant force. As extension at this stage recall Newton's second law and think
about what a constant force form the fan will do to the motion of the cart.

Watch
K2D3_results.swf and check your prediction. Alter your graph if necessary to
fit your observations. **
Note:** The linear sections
of the graph that are shaded is what we are interested in. As an extension see
if you can understand the non-linear sections of the graph. These involve
acceleration and deceleration of the cart by Professor Thornton. Recall the
convention we have used for direction (+ = right and - = left from our point of
view).

Watch
K2D3_interp.swf and make notes on your sheet if necessary following this
video. **Note:**
Recall that any force, motion or acceleration to the right is positive. When the
fan is applying a force to the cart to the right it accelerates the cart to the
right and the velocity of the cart is to the right and increases. This means
that both the acceleration and the velocity are positive.

**Demonstration 4**

Watch K2D4Intro.mov and record your prediction on sheet 2.

Watch K2D4_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch
K2D4_interp.swf and make notes on your sheet if necessary following this
video. **Note:**
Recall that any force, motion or acceleration to the right is positive and to
the left is negative. Professor Thornton accelerates the cart at the start of
the demonstration and then the constant force to the left (negative direction)
from the fan decelerates the cart. So the velocity starts out positive and
reduces to zero. Since the force acting on the cart is to the left the force is
in the negative direction and the deceleration of the cart (slowing down) that
is caused by this net force is therefore a negative acceleration (an
acceleration in the negative direction). This is because a deceleration (slowing
down) is just an acceleration in the direction opposite to the motion of the
object. When the fan is applying a force to the cart to the left it accelerates
the cart to the left. Since the velocity of the cart is initially to the right
and the velocity decreases because there is a net force acting to the left. In
this situation the velocity is always positive and the acceleration is negative.

**Demonstration 5**

Watch
K2D5Intro.mov and record your prediction on sheet 2.
**Note:**
The notes above in demonstration 4 may come in handy if you run into trouble
with this demonstration.

Watch K2D5_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K2D5_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 6**

Watch K2D6Intro.mov and record your prediction on sheet 2.

Watch K2D6_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch
K2D6_interp.swf and make notes on your sheet if necessary following this
video. **Note:**
It is important to understand simply why the acceleration is constant throughout
the motion of the cart in this example. Professor Thornton tells you simply that
the velocity is always changing so even at the instant the cart sits still it is
still accelerating. This is because before that instant it was moving and after
that instant it is moving again so it is always changing its velocity. Therefore
it is accelerating the whole time in the positive direction. It's acceleration
is opposite to the direction of motion initially so the cart slows down and then
the acceleration is in the same direction to motion so it speeds up. The
direction of the acceleration does not change but the acceleration changes the
direction of the motion after the cart comes to rest.

**Demonstration 7**

Watch K2D7Intro.mov and record your prediction on sheet 2.

Watch K2D7_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K2D7_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 8**

Watch
K2D8Intro.mov and record your prediction on sheet 2.
**Note:**
When Professor Thornton refers to the origin he means that this is the point of
reference. We make our measurements from that point or with respect to that
point. In this case the origin is on the floor so the ball moves away from the
origin (in the positive direction) as it moves up and towards the origin (in the
negative direction) as it moves down.

Watch K2D8_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch K2D8_interp.swf and make notes on your sheet if necessary following this video. Note: Look back over activties 3 to 8 and you notice that all these situations involve constant acceleration. What is happening to the magnitude of the net force acting in all these situations? Especially interesting is the fact that gravity exerts a constant net force downwards on any body and when the body is unsupported (free to fall) it accelerates downwards i.e. in this case the acceleration is always downwards (negative in this case) and causes the ball to slow down, change direction and then speed up.

**Newton's First and Second Laws**

Watch
L3D1GIntro.mov to get a general introduction to the activities that follow.
**Note:**
Recall Newton's First and Second laws.

**Demonstration 1**

Watch L3D1Intro.mov and record your prediction on sheet 3.

Watch L3D1_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L3D1_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 2**

Watch L3D2Intro.mov and record your prediction on sheet 3.

Watch L3D2_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L3D2_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 3**

Watch
L3D3Intro.mov and record your prediction on sheet 4.
**Note: **
The cart used in this demo has a fan attached to each each end of the cart. The
fans are pointing in opposite directions and they can both apply the same force
on the cart but in opposite directions.

Watch L3D3_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L3D3_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 4**

Watch
L3D4Intro.mov and record your prediction on sheet 4.
**Note:**
In this demo predict the v, F and a during the time the cart is pulled and
immediately after. Assume that the force is applied and released instantly. So
we will predict the ideal case but in reality we know it will be a little
different. As an extension explain the difference between this ideal case and
reality.

Watch L3D4_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L3D4_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 5**

Watch
L3D5Intro.mov and record your prediction on sheet 4.
**Note:**
Make your prediction for after Professor Thornton has pushed the cart towards
the motion detector.

Watch L3D5_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L3D5_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 6**

Watch L3D6Intro.mov and record your prediction on sheet 4.

Watch L3D6_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L3D6_interp.swf and make notes on your sheet if necessary following this video.

**Newton's Third Law**

Watch L4D1GIntro.mov to get a general introduction to the activities that follow.

**Demonstration 1**

Watch L4D1Intro.mov and record your prediction on sheet 4.

Watch L4D1_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D1_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 2**

Watch L4D2Intro.mov and record your prediction on sheet 4.

Watch L4D2_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D2_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 3**

Watch L4D3Intro.mov and record your prediction on sheet 4.

Watch L4D3_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D3_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 4**

Watch L4D4Intro.mov and record your prediction on sheet 4.

Watch L4D4_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D4_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 5**

Watch L4D5Intro.mov and record your prediction on sheet 4.

Watch L4D5_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D5_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 6**

Watch L4D6Intro.mov and record your prediction on sheet 4.

Watch L4D6_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D6_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 7**

Watch L4D7Intro.mov and record your prediction on sheet 4.

Watch L4D7_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D7_interp.swf and make notes on your sheet if necessary following this video.

**Demonstration 8**

Watch L4D8Intro.mov and record your prediction on sheet 4.

Watch L4D8_results.swf and check your prediction. Alter your graph if necessary to fit your observations.

Watch L4D8_interp.swf and make notes on your sheet if necessary following this video.

Any feedback on this activity please email jstanger@sghs.nsw.edu.au