Activity 1: SLINGSHOT CAR
Background Information: Many machines are useful because they convert one form of energy into another form of energy. One example of this is a slingshot, which converts potential energy into kinetic energy to launch a projectile. Potential energy is stored energy, like the energy in a stretched rubber band. As soon as the rubber band is released, the stored potential energy is converted into kinetic energy, or energy in motion, which transfers to the projectile making it move. Kinetic energy can be used to make vehicles move.
This slingshot car activity also demonstrates Newton’s Third Law of Motion-for every action, there is an equal and opposite reaction. When you pull the slingshot car and release it, the backward force applied to the band results in an equal force propelling the car forward.
STEM Career Connections: Automotive engineers design, construct, test, and improve cars and car parts. They focus on how the vehicles perform and look. They also work with the electronics and software systems within cars and car parts. Automotive engineers work on all parts of a car, making sure everything works together smoothly.
Materials Needed: 1 cardboard rectangle, scissors, ruler, 2 straws, tape, sandpaper, 2 skewers, 1 rubber band, pencil, 4 pulley wheels
Directions:
Tape one straw along the short edge of the cardboard rectangle as shown. Trim the straw so that it is the same length as the rectangle.
Tape the other straw to the other end of the rectangle so that the straws are parallel to each other. Trim this straw as you did in step 1.
Cut the pointy tip off of a skewer. Then, cut the skewer in half so that each piece is 5.5 inches long.
Slide one skewer through each straw so that a bit of the skewer is sticking out of each end.
Place one pulley wheel onto the end of each skewer by sliding the skewer into the hole in the center of each wheel.
HINT: If the skewer is too big to fit through the hole of the pulley wheel, use sandpaper to make the skewer a bit skinnier so that the pulley wheel fits on it. If the pulley wheel fits loosely on the skewer, wrap a small piece of tape around the skewer to make it a bit bigger.
Flip the rectangle over so that the wheels are touching the work surface. This is the base of your car. Give the car a little push to be sure that it rolls. Make adjustments as necessary.
Tape a rubber band to the middle of one of the short ends of the cardboard rectangle on the top of the car. Secure the rubber band well, as this will be used to launch the car.
Securely tape a pencil or marker to the floor. Hook one end of the rubber band on one end of the pencil/marker. Pull back on the car to stretch the rubber band. Release the car and watch it move.
What can add to or change about your slingshot car to improve it? Give it a try!
Activity 2: MAKE A MODEL TRANSMISSION
Background Information: A transmission is a crucial part of a vehicle that transfers power from the engine or battery to the drive axles and wheels, enabling the vehicle to move. Transmissions harness the power created by the engine or battery, transforming it into controlled "transmissions" of continuous energy. This power is distributed to all connected parts, enabling the vehicle to be driven precisely when, where, and at the speed desired. A vehicle’s transmission maximizes an engine’s efficiency while ensuring power is effectively generated and transferred. Transmissions are used worldwide in a wide range of vehicles.
For this activity, you will build a model transmission with one gear ratio. As you spin one gear, observe how the transferred power affects the speed of the other gear.
STEM Career Connections: A variety of engineers are involved in the creation, testing, and manufacturing of vehicle transmissions, including mechanical, manufacturing, and quality engineers. Mechanical engineers design power-producing machines. Manufacturing engineers develop tools, processes, machines, and equipment used in the production of goods. Quality engineers oversee a company’s manufacturing and engineering processes by ensuring the proper use of tools, materials, and procedures
Materials Needed: 1 cardboard rectangle, scissors, ruler, 1 straw, tape, sandpaper, 2 skewers, 1 rubber band, pencil, 3 pulley wheels
Directions:
Cut 4 1-inch long pieces of straw.
Tape one straw piece to the left and one straw piece to the right of the cutout, about 1 inch up from the bottom of the cutout, as shown, so that the straw openings are lined up.
Tape the other two straw pieces to the cardboard in the same way as the previous step, about 1.5 inches above the original straws.
Take one pulley wheel and place a rubber band in the groove around it.
Take one skewer and slide it through one of the straws near the bottom. Then, slide the skewer through the pulley wheel with the rubber band on it, and then slide the skewer through the other straw. The pulley wheel with the rubber band should be positioned in the middle of the opening.
NOTE: If the skewer is too big to fit through the hole of the pulley wheel, use sandpaper to make the skewer a bit skinnier so that the pulley wheel fits on it.
Take the remaining skewer and slide it through one of the top straws, then pull the rubber band from the wheel and slide the skewer through it and the remaining straw. When the top skewer is in place, the rubber band should be tight. If it is not, move the two top straw pieces up a bit.
Take the remaining two wheels. Attach one to the top left of the top skewer, and the other to the bottom right of the bottom skewer.
Pick up the model transmission and hold it one hand. With your other hand, spin the bottom skewer. Since the rubber band connects the two skewers, both skewers should spin when the bottom skewer is spun.
What else do you notice as you compare how the wheels on each skewer spin?
Activity 3: NEWTON’S CRADLE
Background Information: A Newton's cradle is a fascinating device that shows a couple of science concepts in action. It was named after the famous scientist, Sir Isaac Newton, though he did not invent it. A Newton’s cradle demonstrates the principle of conservation of momentum (an object’s mass times velocity) through its swinging spheres. When a sphere at the end is lifted and then released, it collides with the stationary spheres, transmitting a force that propels the last sphere upward. This sphere then swings back and impacts the nearly motionless spheres, repeating the effect in the opposite direction.
A Newton’s Cradle also demonstrates kinetic and potential energy transfers. As you hold the first sphere up in the starting position, it is motionless but has stored (potential) energy. When the sphere is released and moves downward due to gravity, the stored potential energy converts to kinetic energy, or energy in motion. When the moving sphere strikes a stationary sphere, the kinetic energy from the moving sphere transfers to the stationary sphere, giving it kinetic energy and causing it to move. This continues down the line.
STEM Career Connections: Materials engineers study and test materials such as metals, plastics and ceramics to develop new materials for use in all kids of products. Their main goal is to alter materials to create new options that are safer, stronger, and more useful and efficient.
Materials Needed: 16+ popsicle sticks, 4-5 marbles (all the same size), string, ruler, scissors, tape
Directions:
Create a base structure for the Newton’s cradle using 12+ large craft sticks, securely taping them together as shown. Use additional craft sticks and tape to reinforce the structure to make it sturdy.
Cut string into 5 equal pieces approximately 8-10 inches long.
Use a very small piece of tape to tape one marble to the center of one of the pieces of string. Repeat until you have 5 separate marbles, each taped to the center of its own string.
NOTE: Try to keep the tape at the top of the marble only, so that each marble strikes the marble next to it directly, not the tape holding the marble to the string.
Tape one end of the first marble string to the center of one of the flat craft sticks at the top of the base structure. Tape the other end of the string to the flat craft stick on the other side so that the marble hangs in the middle.
Hang the other marble strings in the same way so that each marble is touching the marble(s) next to it. The marbles must line up both horizontally and when viewed from the top.
Test the Newton’s cradle by lifting a marble on one end so that the marble is approximately equal in height to the top of the base and the string is taut (tight). Release the marble and watch what happens.
The marbles should swing and hit each other, causing the next marble to move. Make adjustments to the cradle to improve the way it works.