VOC
What is the LAW OF CONSERVATION OF ENERGY?
Energy cannot be created or destroyed; it can only change form.
What two things does momentum depend on?
Momentum depends on mass and velocity.
What is the difference between an ELASTIC collision and an INELASTIC collision?
An elastic collision is one where there is no loss of kinetic energy from the system.
An inelastic collision is one where some kinetic energy is transformed into other types of energy.
What happens to a roller coaster's kinetic energy as it moves up a hill?
The kinetic energy transforms into potential energy.
A student says: 'When the car stopped, the block's inertia was destroyed.' Is this correct? Fix the error.
No. Inertia is not destroyed. The car's inertia was changed by the force of the collision. The block's inertia kept it moving forward.
What is KINETIC ENERGY and POTENTIAL ENERGY?
Kinetic energy is the energy of motion.
Potential energy is stored energy.
How does increasing the mass of an object affect its momentum?
Increasing the mass increases the momentum.
(so long has it has some velocity)
What toy is used in the textbook to demonstrate elastic collisions?
Newton's cradle.
In Newton's cradle, what happens to energy over time?
The balls decrease in height and eventually stop. Some energy is transformed into sound and heat each time the balls collide.
A football player with high momentum collides with a lighter player standing still. What likely happens and why?
The lighter player will likely be pushed back or knocked over. The player with greater momentum transfers more energy and force.
What is MOMENTUM?
Momentum is a measurement of how easy or difficult it is to stop a moving object.
It is calculated by multiplying mass and velocity.
How does decreasing the velocity of an object affect its momentum?
Decreasing the velocity decreases the momentum.
Are most real-life collisions elastic or inelastic?
Most real-life collisions are inelastic.
A student claims energy was lost in a Newton's cradle collision because the balls slowed down. Correct this student's thinking.
Energy was not lost — it was transformed. The kinetic energy converted into heat and sound, which is consistent with conservation of energy.
If a small car collides with a large truck moving at the same speed, which has more momentum and what happens?
The truck has more momentum due to greater mass. More energy transfers from the truck to the car, causing the car to move or deform more.
What is INERTIA?
Inertia is the tendency of an object in motion to stay in motion, and an object at rest to stay at rest.
Explain why a heavy, fast-moving object is harder to stop than a light, slow-moving one.
Because momentum = mass × velocity. Greater mass and greater velocity both increase momentum, making it harder to change the object's motion.
Why do the balls in Newton's cradle eventually stop if it is not perfectly elastic?
Each collision transforms some energy into sound and heat, so total kinetic energy decreases over time.
Why does a roller coaster slow down even though energy is conserved?
The lost kinetic energy is not destroyed; it changes into heat and sound through friction.
A student pushes a book across a desk and it slows to a stop. Identify all the energy transformations.
The kinetic energy of the book is converted to heat and sound through friction between the book and the desk. Energy is conserved — just transformed.
What is the difference between an ENERGY TRANSFER and an ENERGY TRANSFORM.
Energy transfer is the movement of energy from one object to another.
Transform means energy changes from one form to another.
If you halved both the mass AND the velocity of an object, what would happen to its momentum?
Momentum would be reduced to one quarter (½ × ½ = ¼), since both factors in the equation are halved.
Imagine a scenario where two objects collide and one stops completely. Which type of collision is this closest to, and what happened to the kinetic energy?
This is inelastic. The kinetic energy was transferred to the other object and also converted to heat and sound.
In a collision, which object transfers more energy to the other — the one with greater momentum or lesser momentum?
The object with greater momentum transfers more energy to the object with lesser momentum.
A heavy shopping trolley full of groceries is rolling slowly down a gentle slope. A lighter empty trolley is rolling faster down the same slope beside it. They reach the bottom at the same time and both hit a wall.
After they hit the wall, the full trolley bounces back less than the empty one. Why might that be?
The heavy trolley is harder to push away again once it stops — its inertia resists the bounce just like it resisted being stopped in the first place. The light trolley doesn't resist as much, so it pings back more easily.