inertia
What is inertia?
Inertia is the tendency of an object to resist changes in its motion.
What is potential energy?
Potential energy is stored energy an object has because of its position or condition.
What is gravity?
Gravity is a force that pulls objects toward each other, such as pulling us toward Earth.
What is kinetic energy?
Kinetic energy is the energy an object has because it is moving.
What is Newton’s Third Law of Motion?
For every action, there is an equal and opposite reaction.
Which law of motion describes inertia?
Newton’s First Law of Motion.
What type of potential energy does a book on a shelf have?
Gravitational potential energy.
What is friction?
Friction is a force that resists motion when two surfaces rub against each other.
What two factors determine an object’s kinetic energy?
Mass and speed.
When you push on a wall, why do you feel the wall pushing back?
Because the wall exerts an equal and opposite reaction force on you.
Why does a passenger move forward when a car stops suddenly?
Because the passenger’s body wants to keep moving at the same speed due to inertia.
If you lift an object higher, what happens to its gravitational potential energy?
It increases because the object is farther from the ground.
Why do objects fall faster on Earth than on the Moon?
Earth has stronger gravity than the Moon, so it pulls objects downward with more force
If two objects move at the same speed, which one has more kinetic energy?
The object with the greater mass.
Why does a balloon fly around the room when the air rushes out?
The air pushes backward out of the balloon (action), and the balloon moves forward (reaction).
A heavy boulder and a small rock are both at rest. Which has more inertia and why?
The boulder has more inertia because it has more mass.
Why does a stretched rubber band have potential energy?
Because work is done to stretch it, storing elastic potential energy that can be released later.
Why does a smooth surface create less friction than a rough surface?
A smooth surface has fewer bumps and irregularities, so it creates less resistance when objects slide across it.
Why does doubling an object’s speed increase its kinetic energy more than doubling its mass?
Because kinetic energy depends on the square of speed, so increasing speed has a much bigger effect.
When a swimmer pushes the water backward with their hands, what is the reaction force?
The water pushes the swimmer forward with an equal and opposite force.
How does inertia explain why a spacecraft in deep space can continue moving at constant speed without using fuel?
In the absence of external forces (like friction or gravity), inertia keeps the spacecraft moving at a constant speed indefinitely.
A 2 kg object is lifted to a height of 5 meters. Using g=9.8, what is its gravitational potential energy?
PE=m⋅g⋅h=2⋅9.8⋅5=98 joules
How do friction and gravity work together when a car drives uphill?
Gravity pulls the car downward, making it harder to climb, while friction between the tires and the road provides the grip needed to push the car upward.
A 3 kg object moves at 4 m/s. What is its kinetic energy?
KE=12⋅m⋅v2=12⋅3⋅16=24 joules
A rocket launches upward by expelling gas downward. Explain how action and reaction forces allow it to lift off even in space where there is no air.
The rocket pushes exhaust gases downward (action), and the gases push the rocket upward with an equal and opposite force (reaction), so it can accelerate even without air.