FarleyPhysics.com

Newton’s Laws Computer simulations

Go to this link http://www.beyondbooks.com/psc91/4a.asp

Answer the following questions:

Who influenced Newton the most?
What does Newton’s First Law state?
What is inertia?
Run Galileo’s Experiment and put the marble at 8 meters.  Explain what happens and draw a picture in your notes.
Run Galileo’s Experiment again with the marble at 8 meters and the angle of the opposing plane at zero degrees.  Explain what happens and draw the picture.

Click the Next button and answer the following questions

What is a force?
What is a Contact Force and list four examples.
What is an Action at a distance force and list three examples

Go to this link and try to find the velocity that makes the cannon orbit the earth in a perfect circle.  It will hit the top of the mountain when it comes back around.  Explain what is happening here and include a picture in your notes.

Go to this link and create a 10 N force on a 10 kg cart. Write the equation, the numbers that went into the equation, the answer, and draw the dots that result.

Create a 40 N force on a 10 kg cart. Write the equation, the numbers that went into the equation, the answer, and draw the dots that result.

Create a 10 N force on a 40 kg cart. Write the equation, the numbers that went into the equation, the answer, and draw the dots that result.

Net Force, Equilibrium, and Free Body Diagrams

Net Force- The combination of all forces on an obect

Equilibrium-When net force equals zero

Examples: A tug of war, a person hanging from a bar, A car accelerating, an airplane taking off, a box on a table, a box on a table being pushed, a box on a table being accelerated.

Do problems 14-17 on page 57 and 33, 34 on page 58.  Draw a free body diagram for each problem.

Quiz

1. Newton’s Second Law: F = ma

2. Solving for F, m, or a

3. Examples

4. Problems

A little boy pushes a wagon with his dog in it.  The mass of the dog and the wagon together is 45 kg.  The wagon accelerates at 0.85 m/s².  What force is the boy pulling with?

A 1650 kg car accelerates at a rate of 4.0 m/s².  How much force is the car’s engine producing?

A 68 kg runner exerts a force of 59 N.  What is the acceleration of the runner?

A crate is dragged across an ice covered lake.  The crate accelerates at 0.08 m/s² and is pulled by a 47 N force.  What is the mass of the box?

3 women push a stalled car.  Each woman pushes with a 425 N force.  What is the mass of the car if the car accelerates at 0.85 m/s²?

A tennis ball, 0.314 kg, is accelerated at a rate of 164 m/s² when hit by a professional tennis player.  What force does the player’s tennis racket exert on the ball?

When an F-14 airplane takes-off and aircraft carrier it is literally catapulted off the flight deck.  The plane starts from rest and reaches 68.2 m/s in 3 seconds.  First, calculate the acceleration of the F-14, then calculate the force needed to launch this 29,545 kg jet into the air.

A sports car accelerates from 0 to 60 mph (27 m/s) in 6.3 seconds.  If the car’s engine exerts a force of 4106 N, what is the mass of the car?  Be sure to find acceleration first.

The Saturn V rocket that went to the moon had 5 rocket engines in its first stage that produced 5,600,000 Newtons of force each. The mass of the Saturn V was 3,084,000 kg.  What was the acceleration of the Saturn V at launch?

Mass is the quantity of matter, or a measure of something’s inertia.

Weight is the force of gravity on an object.  Gravity can change, mass cannot.

The Units of mass and weight.   kg and Newton

Calculating weight given the mass,  calculating mass given weight, and calculating the acceleration of gravity given mass and weight. using w = mg

For all the questions below, use g = 10 m/s/s.  g on the moon is 1/6 what it is on the Earth.

1.  A ball has a mass of 1 kilogram.  Find its weight in newtons.

2. A bag of groceries has a weight of 44 newtons.  Find its approximate mass in kilograms.

3.  A marble has a mass of  0.002 kilograms.  Find its approximate weight in Newtons.

4.  If an object has a mass of 36 kg, find its mass on the moon and find its weight on the moon.

5.  An astronaut has a mass of 90 kg.  Find his mass and his weight if he is in a flight simulator where the gravitational attraction has been reduced to 1/10 of the earth’s pull.

6.  An object has a mass of 5.5 kilograms.  Find its weight in newtons.

7.  A bag of apples has a weight of 22 newtons.  Find its approximate mass in kilograms.

8.  A paper clip has a mass of  0.001 kilograms.  Find its approximate weight  in newtons.

9.  If an object has a mass of 24 kg, find its mass on the moon and find its weight on the moon.

10. An astronaut has a mass of 85 kg.  Find his mass and his weight if he is in a flight simulator where the gravitational attraction has been reduced to 1/10 of the earth’s pull.

Newton’s First Law of Motion (The Law of Inertia)

An object at rest will stay at rest and an object in motion will stay in motion in a straight line unless a net force acts upon it.

Demonstration: Tablecloth trick, flick a ping pong ball or flick a 1 kg mass?  Penny on a card trick.  Swing a bucket of water overhead.

Videos: Inertia Ball, Revolving ball.

Mass–A Measure of Inertia

Mass is not volume and not weight.  It is a measure of the amount of matter in a thing.

Problems: Answer problems 26-32 in the text.  Be sure to include the question in the answer.

Homework: Read pages 43-48 in the book and answer questions 1-8 on page 56.  Be sure to include the question in the answer.

1. Return and discuss quiz

2. Motion detectors

1. Try to recreate the graphs below by moving in front of a motion detector.  Draw the graphs in your notes and describe the motion that you did in order to match each graph.

2. For the last graph, use the Tangent button to find the slope near the beginning of the graph and near the end.  The slope of a position vs. time graph is the velocity.  What is your velocity at the beginning and at the end?  Were you accelerating?  How do you know?

3. What other graphs show you accelerating?  Explain how you know you were accelerating.

4. What other graphs show you not accelerating?  Explain how you know you were not accelerating.

1. Finish video

2. Graphing with Logger Pro

1. Find Logger Pro and start it

2. Add the data you want to graph:

3. Press The Autoscale button

4. Now press the Linear Fit button to find the best fit line through the data.

Draw the chart in your notes as well as the equation and the slope.

5. Change the y data so it is equal to x squared, click Autoscale again, and delete the linear fit box.

6. Click the Curve Fit button

and select “Power” as the equation type.

7. Click “Try Fit” and write down what A and B are as well as the equation with A and B where they belong.  Round your numbers to the nearest whole number for this excercise.

8. Draw your graph and write the equation.

9. Quit Logger Pro and don’t save the project