Tie a string from the support to a large metal ball. Tie a second string to the ball and let it hang. If you pull on the bottom string very quickly, the bottom string will break. If you pull on the bottom string slowly the top string will break. Now attach a spring to the support and have the ball hang on the spring. Tie a string to the second end of the ball. If you pull on the string slowly the spring will stretch and the string won’t break. If you pull quickly, the string will break.
Location: Inertia ball -
C2-07-4
Vertical support - C2-08-2
String-
C2-07-4
Spring-
C2-07-4
Prep time: 5 minutes
This simulation is a ball resting on top of a cylinder with a piece of metal in between. There is a flexible piece of metal near the cylinder. Put the metal sheet on top of the cylinder so it just touches the piece of flexible metal. Make sure the arrow is pointing away. Now pull back on the vertical piece of metal and let go. It will flick out the metal and the ball will fall on the cylinder.
Location: Simulation - ME3E-22-1
Prep Time: none
Place the brick on your hand and deliver a sharp blow with the hammer. The massive brick will want to remain motionless making it possible to dent the metal without hurting your hand. HINT: place your hand palm up and strike the brick more toward the palm than the fingers.
Location: Brick-
ME1C-67-2
Hammer- ME1C-67-2
Prep Time: none
Take three balls and juggle them or have a student juggle. The rate of motion of one’s hand is inversely proportional to the time of flight. Low trajectories require fast juggling while high trajectories allow one to juggle slowly.
Location: Balls - ME2F-06-3
Prep Time: none
Suggested questions:
- Hang a 1-kg mass on a spring scale. What will the scale read?
- Now hang the same mass on a massless rod suspended by two scales in parallel. What is the reading on the scale? Does it change if the mass is not in the middle? What do the scales add up to?
- What do the scales read if they are hung in series and the kilogram hangs from the lower one?
- Now remove the kilogram, attach a string to the hook of the lower scale and exert a tension of 1000 grams. Secure the string to the base of the support stand. Both scales will read 1000 grams, right?
- Next add 400 grams of mass to the hook on the lower scale. What will this do to the scale readings?
- What would the scales read if you hung the mass to the upper scale? Why is this different to the previous situation?
Location: Rods –
C2-02-1
Balances – C2-02-1
Masses – C2-02-1
String – C2-02-1
Prep Time: none
