Work, energy, power

Question 1

What is energy?

Answer 1

Energy is the ability of a physical object / system to cause change.

Question 2

What are the 2 types of energy?

Answer 2

Kinetic and Potential

Question 3

S.I unit for energy

Answer 3

Joules (J)

Question 4

Describe the law of conservation of energy in words and mathematically

Answer 4

In any transfer or transformation, the total energy remains unchanged. The energy before the transfer or transformation is the same as the energy after the transfer or transformation. Σ𝐸_i =Σ𝐸_f.

Question 5

What is the mechanical energy.

Answer 5

The total energy of a system or object. It’s equal to kinetic + potential energy

Question 6

Formula for kinetic and potential energy?

Answer 6

Ek = 1/2mv^2 and Ep = mgh

Question 7

What is work and its formula

Answer 7

Work is the energy transferred to an object, usually by applying a force parallel to its displacement:
𝑊=Δ𝐸=𝐸_f −𝐸_i
𝑊=𝐹𝑠

Question 8

How is positive and negative work done?

Answer 8

If the force is applied in the same direction as the displacement, positive work is done; if it is applied in the opposite direction, negative work is done.

Question 9

What is power, it’s formula and S.I units?

Answer 9

Power is the rate at which (i.e. how quickly) work is done:
𝑃=𝑊/𝑡 = Δ𝐸/𝑡

Question 10

What are the 2 collision types?

Answer 10

Elastic and inelastic.

Question 11

What is elastic collision?

Answer 11

In an elastic collision, total kinetic energy is conserved: none is lost to heat / sound / deformation / etc.

Question 12

Inelastic collision?

Answer 12

In an inelastic collision, total energy is conserved, but some kinetic energy is converted to a different form (see examples above).

Question 13

What is a perfectly elastic collsiion?

Answer 13

In a perfectly inelastic collision, the two objects stay together after the impact.