Playground Physics

Before going to the playground consider the following concepts you should already know about mechanics, discuss how each of these could be demonstrated on a playground.

Potential Energy

 

Kinetic Energy

 

Newton's 1st Law (Inertia)

 

Centripetal Force

 

The following tests can be done in any sequence, divide the class up into small groups.

1. Measure the Length of the swing (measure the ropes or chains) _________
2. Find the Mass of the person swinging ________

3. Estimate how high the person can swing using a meter stick.____

4. Calculate the potential energy of the person at this height:

PE = mgh

 

5. At this point, the swinger should relax and allow the swing to move back and forth without using their legs to make it go higher.

Determine the PERIOD of the pendulum (swing) by timing how long it takes for the swinger to make a complete back and forth swing. ______________ (seconds)

Determine the time it takes for the person to make 5 complete swings _____________ (seconds)

6. Calculate the VELOCITY of the swinger.

Velocity = distance / time

Distance = length of the swing's chain _________

Time = The time it takes for the swing to go from one side to the other side. ______

Velocity = ________

(Show Work)

7. Now Calculate the KINETIC ENERGY of the swinger

KE = _______________ (show work)

Your playground may have several slides to run these tests on. A spiral slide will work but it must be treated a little differently than a straight slide. Your goal is to find the potential energy of a rider at the top of the slide and the kinetic energy of the person at the bottom of the slide.

1. Potential Energy - Measure the height of the slide _________

2. Measure the length of the slide (if you are using a spiral slide, use a length of string to measure the distance of the slide as it goes around the corksrew) _________________

3. Measure the mass of the person riding: __________________
*Alternative, use a ball or other object to slide (roll) down the slide.

4. Calculate Potential Energy (show work)

PE = mgh

PE = ___________

5. Calculate the Velocity

Measure the Velocity of the rider by timing how long it takes a person to complete the slide. Divide the distance of the slide by this time.

V = distance / time

V = _____________________

6. Calculate Kinetic Energy using the velocity you determined above

KE = __________ (show work)

1. Measure the radius of the merry go round (center to outside edge) ____________
Measure the circumference of the merry go round using string _____________

2. This test will require four people working together. Two will be sitting on the merry go round, and another is needed to time the spins. Have one person sit in the center and another toward the outside. Spin the merry go round and measure how long it takes for each rider to make 3 complete spins

Time for Center Rider ______________ Time for Outer Rider ____________
Which person is traveling faster? ______________________

3. Calculate the velocity of the outer rider.

Spin the Merry Go Round and time how long it takes for the rider to complete a single turn. _______
The distance the rider traveled is the circumference _________

Velocity = distance / time = ___________________

Mass of the outer rider = __________________

4. Calculate the Centripetal Force

(Use numbers you calculated above)

5. Can you catch a tennis ball?

With two riders on the merry go round, try tossing a tennis ball back and forth. Describe (or sketch) the path the ball takes as you pass it to the other person.