Energy and Motion
What is energy?
Energy is the ability to do work or cause change.
What is a collision?
A collision happens when a moving object hits another object.
What types of energy can be produced during a collision?
• Sound energy (a bang or thud)
• Heat energy (objects warm up)
• Light energy (sometimes, like sparks)
What is an electric current?
An electric current is the flow of electric charge.
What always happens to energy when it is transferred or changed?
Energy is always conserved.
Two objects move at the same speed. One is lighter. Does it have more or less kinetic energy?
The lighter object has less kinetic energy.
What usually happens when two objects collide?
Energy is transferred, and the objects’ motion changes.
What can carry energy without objects moving from place to place?
• Sound
• Light
• Heat
What does a solar cell do?
A solar cell changes light energy into electrical energy.
When people say energy is “used up,” what is really happening?
The energy is being transferred or changed, not destroyed.
How can a ball be given stored energy (gravitational potential energy)?
Lift it up to a high shelf.
A moving object hits a still object of the same mass. What happens to each object?
The moving object slows down, and the still object starts moving.
All sound starts with what?
All sound starts with vibrations.
What does a generator do?
A generator changes motion (kinetic energy) into electrical energy.
What object does not have stored energy between a:
1. tank of gasoline
2. rock on the ground
3. dam holding water
4. charged battery.
2 - rock on the ground
When an object moves slower, does its kinetic energy increase or decrease?
decreases.
A moving object hits a still object. What must be true for the still object to move away at the same speed?
Both objects must have the same mass.
What happens when light bounces off of an object?
The light is reflected.
What is a motor?
A motor is a device that changes electrical energy into motion.
What is a nonrenewable resource?
A nonrenewable resource is a natural resource that cannot be replaced quickly once it is used up. This could be coal, oil, or natural gas.
How can an object increase its kinetic energy?
By moving faster or by having more mass.
Two objects have the same mass but are moving at different speeds. They collide head on. What happens to their speeds?
They exchange speeds. Each object bounces back with the other object’s speed.
What would make solar panels LESS effective?
Solar panels are less effective when less sunlight reaches them.
Shade (trees, buildings, clouds) 🌳
Low sunlight (nighttime, winter, short days) 🌥️
Panels not facing the Sun (wrong angle or direction) 📐
Dirty or dusty panels (grime blocks light) 🧼
Snow covering panels ❄️
What is an "energy-efficient" device?
An energy-efficient device is a device that wastes very little energy and most of the energy goes to the purpose of the device.
The first step engineers take when designing a solution is to do what?
The first step engineers take is to identify (define) the problem. They learn the requirements and constraints before building anything.