physics week 10 part 1

Kinetic Energy

Energy possessed by an object due to its motion.

What type of quantity is energy?

Energy is a scalar quantity, meaning it has magnitude but no direction.

What aspect of an object's movement is relevant for kinetic energy?

Only the speed of the object matters for kinetic energy, not velocity.

What is a common mistake when thinking about energy?

Students often incorrectly relate energy with components of velocity (x or y components), but energy does not depend on direction.

Relationship between Work Done and Kinetic Energy

Work done on an object is directly equivalent to the change in its kinetic energy.

What happens to an object's kinetic energy if a net force causes work on it?

If a net force causes work on an object, it will result in a change in kinetic energy.

What effect does negative work have on an object's kinetic energy?

When a force applies negative work, it causes a decrease in kinetic energy.

How is kinetic energy related to speed?

Kinetic energy is directly related to the square of the speed.

If an object's speed doubles, how does its kinetic energy change?

If an object's speed doubles, its kinetic energy becomes four times greater.

Is friction considered in initial kinetic energy calculations?

At this initial stage, friction is not taken into account.

What are the two primary forms of energy?

Kinetic Energy and Potential Energy.

Potential Energy

Energy of position or configuration.

Conservative Forces

Forces for which the work done is path-independent, only depending on initial and final positions.

Examples of conservative forces

Gravitational forces and spring forces.

On what does the work done on a spring depend?

The work done on a spring solely depends on the initial and final lengths relative to the rest position.

What is often chosen as the zero potential energy reference point for gravitational potential energy?

The ground is often chosen as the zero potential energy reference point.

Can potential energy be negative?

Yes, potential energy can be negative if moving below the reference point.

What happens to potential and kinetic energy when an object falls?

When an object falls, its potential energy decreases while its kinetic energy increases.

What is conserved if only conservative forces are acting?

The total mechanical energy (E_{total}) which is the sum of kinetic and potential energy (KE + PE) is conserved.

What parts of motion are irrelevant when using energy methods compared to kinematic approaches?

The x and y components of motion are irrelevant when utilizing energy methods.

What are key problem-solving strategies for energy problems?

Drawing a diagram and identifying events to establish characteristics at different points.