Power is rate at which energy is transferred or used up
Work done = force x distance moved by object
Energy transfer occurs when work is done, such as moving an object against friction.
Equation for distance travelled
distance travelled = speed × time
What eventually happens to wasted energy?
dissipates into the surroundings
efficiency (%) = useful output / total input × 100%
Write down the equation which links gravitational field strength, gravitational potential energy, height and mass.
g.p.e. = mass × gravitational field strength × height
Momentum
product of mass and velocity
Calculate momentum
P=mv
Momentum=mass x velocity
What has happened to the rest of the energy from a gunshot?
Transferred into heat and sound
The miners working in a salt mine use smooth wooden slides to move quickly from one level to another. The speed of the miner at the bottom of the slide is much less than the calculated maximum possible speed. Explain why
work is done against friction so the slide not smooth causing energy to be transferred as heat energy of surroundings
change in thermal energy, ∆E, in joules, J
mass, m, in kilograms, kg
specific heat capacity, c, in joules per kilogram per degree Celsius, J/ kg°C
temperature change, ∆T, in degrees Celsius, °C
If a large amount of energy is required to heat up a substance, then its specific heat capacity will be very high
If a small amount of energy is required to heat up a substance, then its specific heat capacity will be very low.
If two objects have the same speed, the heavier object has more kinetic energy.
If two objects have the same mass, then the faster moving object has more kinetic energy.