Instantaneous power

Definition

Instantaneous power is the rate at which work is done or energy is transferred at a specific moment in time. It is mathematically defined as the derivative of work with respect to time or the product of force and velocity.

5 Must Know Facts For Your Next Test

1. Instantaneous power can be calculated using the formula $P(t) = F(t) \cdot v(t)$, where $F(t)$ is the instantaneous force and $v(t)$ is the instantaneous velocity.
2. It differs from average power, which measures the rate of work done over an interval of time.
3. In electrical systems, instantaneous power is given by $P(t) = V(t) \cdot I(t)$, where $V(t)$ is instantaneous voltage and $I(t)$ is instantaneous current.
4. The SI unit for instantaneous power is the watt (W), which equals one joule per second.
5. Graphically, the area under a power vs. time curve represents the total work done over that period.

Review Questions

• What is the formula for calculating instantaneous power in mechanical systems?
• How does instantaneous power differ from average power?
• What are the SI units used for measuring instantaneous power?

Related terms

Work:

The transfer of energy by a force acting over a distance. It’s calculated as $W = F \cdot d \cdot \cos(\theta)$.

Energy:

The capacity to do work. Common forms include kinetic energy, potential energy, and thermal energy.

Velocity:

A vector quantity that denotes the rate of change of position with respect to time. It has both magnitude and direction.