Force and Gravity
Fist and Fingers: One person will hold their arms out
straight, making fists with their hands. While pushing their fists
together tightly, another person will take their two index fingers
and separate the fists by pushing from each side.
Dollar Drop/ Reaction Time: One person will hold a dollar bill
from the top in a horizontal position. Another person will rest their
elbow on a table and position their hand above the head holding their
thumb and bird finger about an inch apart. When the first person
drops the dollar, the other will try to catch the it before it falls
to the ground.
Why does the stream of water from a faucet get smaller as it goes
down ? As the water falls, it's speed is increasing. Since the volume
of the water remains the same, each second the distance the water
falls becomes greater making the stream smaller as it goes down.
Double a rope and get lots of kids pulling on each end and see if two
kids can pull the center of the ropes apart.
Physics for every kid pg 126- tug of war.
Drop different sized objects together to see which wins.
Friction
101 Tricks Pg 12 & 13
1) Place a number of different objects such as an eraser, coin,
bottle cap, ice cube at the same end of a smooth plane. Slowly lift
the board creating an incline and watch the objects as they begin to
move down the plane. Which has the lowest friction? Which has the
greatest grip?
2) Place motorized toy cars on incline and tilt it until they
barely go up the incline. Then, put cellophane tape on rear tires and
try again. Observe how the surface will make the wheels spin on the
cars as the friction is reduced.
3) Place a streamlined foil over a toy car and a square foil over
another one. Put the cars on an incline and allow them to travel down
it. Use a blow dryer to create air resistance for the cars, and see
which one will go the fastest.
101 Tricks Pg 9
1) Drop a flat piece of paper and a piece of paper that has been
rolled into a ball. Which one will fall to the floor the fastest and
why? Discuss the air resistance and relationship to mass and surface
area.
2) Cut a large circle from a plastic bag. Cut six pieces of string
the same length. Tape each string to the edge of the circle and tie
the other ends together around a small toy. Throw the parachute high
into the air and watch it float to the ground. Discuss the drag or
air resistance. (See also Turning the world inside out pg 44.)
Phy for Every Kid Pg 159- Build a tiny
hovercraft
1) Cut a 4-in. square piece of cardboard and poke a hole through the
center of it using a pencil. Glue an empty thread spool over the hole
in the box, lining up the two holes. Place a bead of glue around the
base of the spool. Cut and glue a circle of paper over the top of the
thread spool and allow several hours to dry. Using a pencil, punch a
hole in the paper that lines up with the hole in the spool. Place the
cardboard on a smooth surface and give it a push to observe its
motion. Then, inflate a balloon and twist the end. Stretch the
opening over the top of the spool. Untwist the balloon and give the
cardboard a push. Notice that the cardboard moves much faster now.
Why? Discuss the friction of the two surfaces.
2) Fill a narrow necked flask full of rice. Jab it several times with
a knife, then plunge knife in and pick up the flask with it. Discuss
how friction allows you to pick up the flask.
Inertia
Martin Gardner pg 41 & 45
1) Put a marble at the bottom of a drinking glass and fill it full of
rice. Rest the glass on one palm and tap the brim rapidly with the
other palm. The marble will rise to the surface
.
2) Cut rectangular piece of paper in thirds, almost. Holding on to
the two end pieces, try to jerk so all three come apart. Next, tape
or paper clip a half dollar to the middle third and try again.
Discuss how the increase in the middle pieces inertia causes the
pieces to break in both places.
3) Tie a heavy object such as a book to a string and suspend it in
midair. Tie another piece of string to the object and let it hang.
Jerk on the dangling string to see which one will break. Discuss how
the inertia of the object causes the bottom string to break.
4) Balance a card on your index finger. Place a quarter on top of the
card. Try to flick the card off your hand without moving the quarter,
or do same with an object on top of a card on top of a glass.
Newton's Third Law
Build a balloon rocket
Pull two scales connected together: Note they always read the
same.
Push two bathroom scales together, note they too always read the
same.