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Physics L5-6, Link Title - Coggle Diagram
Physics L5-6
Lesson 5
Work Done
Imagine you're pushing a box across the floor. The harder you push (the more force you apply), and the farther you push it (the greater the distance it moves), the more work you do.
Or Work done = F x d (in the direction of the force)
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Kinetic Energy
Kinetic energy is energy possessed by an object due to its motion.
- The kinetic energy (KE) of an object with mass m travelling with velocity v is given as: KE = 1/2mv^2
Power
Power is like how fast or how much work you can do in a certain amount of time. It's a measure of how quickly energy is transferred or used.
- Power = Work Done / Time
- Power = Force x Velocity
Conservation Of Energy
- Energy cannot be created or destroyed.
- Energy can be converted from one form to another.
- Total energy in an isolated system is constant.
When a stationary object fall from a certain height,
- Gravitational Potential Energy to Kinetic Energy
Another example, when the electric motor pull the lift upwards from rest,
- Electric Energy to Gravitational Potential Energy + Kinetic Energy
Momentum
Momentum is basically how hard it is to stop something that's moving. It depends on how heavy the thing is and how fast it's going.
So, the heavier and faster something is moving, the more momentum it has. And if you want to change its motion, you have to push or pull on it to change its momentum.
p (momentum) = m (mass) x v (velocity)
Elastic Collision
- If the total kinetic energy is conserved, i.e. kinetic energy is the same before and after the collision, the collision is known as an elastic collision.
- An elastic collision loses no energy.
- Elastic collisions conserve both momentum and kinetic energy.
Lesson 6
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Behavior of Light
Reflection
Laws of Reflection
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Incident ray, reflected ray and normal lie on the same plane
Refraction
Laws of Refraction
The ratio sine of the angle of incidence to the sine of the angle of refraction is a constant, called the refractive index
The normal, the incident ray, and the refracted ray lie in the same plane.
Refractive Index
high refractive index: When light ray passes through a substance with higher refractive index, it slows down, bending towards the normal.
low refractive index: When light ray passes through a substance with lower refractive index, it speeds up, bending away from the normal.
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