Prepared hands-on materials, full year grade-specific curriculum, and personalized live professional development designed to support mastery of current state science standards.
Chad owns an electric car. In 2010, Chad took a road trip. He drove from the state of Washington to California. He never had to stop for gas. Instead, he plugged his car into electrical outlets he found in campgrounds. This is similar to how you charge your phone.
Electric cars have electric motors. They don’t need gasoline or diesel to run. Instead, they use electricity to make the motors turn.
How an Electric Car Works
The electric motor is part of a circuit that includes a power source such as a rechargeable battery. The motor spins when the circuit is closed. The motor spins as the electrical energy turns into kinetic energy. This spinning provides an unbalanced force that makes the wheels move the car.
The motor is connected to an axle using gears. This motor axle is called the driveshaft. The driveshaft is connected to another axle that is connected to the wheels. The wheels spin when the axle spins.
All of the parts on the vehicle are placed to balance the car’s weight. If a vehicle’s center of gravity is too high, or too close to the front or back, it is unbalanced. This might cause it to roll over when going around sharp turns.
Designing an Electric Car
All objects have a point inside them that is their center of gravity. Imagine trying to balance a ruler on your finger. The point on the ruler where it balances is its center of gravity.
The lower your center of gravity is, the easier it is to keep your balance. Think about leaning over to pick something up. It’s easier to stay balanced if you’re sitting in a chair and you lean over, compared to if you’re standing up.
Cars are designed low to the ground so they have a low center of gravity. However, the center of gravity is not always in the middle of an object. Imagine trying to balance a hammer on your finger. Your finger will have to be closer to the heavier part of the hammer to balance the hammer’s weight.
Friction and Cars
People who design cars also have to take into account friction. Friction is the force that slows motion when two objects rub against each other. Friction makes the objects slow down because the kinetic energy that powers their movement has changed to heat.
Friction between the road and tires is called traction. Cars have tires with treads that are designed to grip the road. This traction is important. It keeps cars from sliding all over the road. This is similar to how the friction between your shoes and the cement stops you from slipping when you run down the sidewalk. When a driver pushes on the brakes, the friction between the brakes and the wheels slows it down.
Some cars use rear-wheel drive. Rear-wheel drive sends power through the rear wheels. Rear-wheel drive offers the best traction for acceleration. Acceleration is an increase in speed over time. It is measured in meters per second squared (m/s2).
When the car accelerates, the car transfers weight toward the rear wheels and away from the front wheels. This extra force pushes the rear tires into better contact with the pavement.
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Discover hands-on screens-off core science curriculum for student centered K-8 classrooms. KnowAtom supports classrooms with all hands-on materials, curriculum, and professional development to support mastery of the standards.
