ENERGY AND WORK Flashcards
energy transferred =
work done
W = Fs
work done (joules,J) = force (newtons,N) x distance (metres,m)
what happens when an object is moved by a force?
work is done on the object by the force, so the force transfers energy to the object
what is applied to move something?
force is applied so energy is transferred as you do work
1 kJ =
1000 J
investigating work
using a newton-meter to measure the force applied and a metre ruler to measure the distance moved
- drag a small box using a newton-meter at a measured distance across a rough surface
- repeat the test with two rubber bands around the box
what happens when work is done to overcome friction?
the energy is mostly transferred to thermal energy stores by heating
explain what happens when you rub your hands together vigorously?
your muscles do work to overcome the friction between your hands and is transferred as energy that warms your hands
explain what happens when a vehicle applies its breaks for too long?
the break pads become hot and the force of friction does work on it between the break pads and the wheel discs which opposes the motion of the wheels
- energy is then transferred from the kinetic energy store of the vehicle to the thermal energy store of the break pads and the wheel discs
- it becomes hot and transfers energy by heating to the thermal energy store of the surrounding air
explain the process of a meteorite entering the Earth’s atmosphere?
they’re small objects from space that pass through the atmosphere and friction caused by air resistance acts upon them
- energy is transferred from the meteorite’s thermal energy store
- if it heats up enough, it glows and becomes like a ‘shooting star’
- very small objects can easily burn up completely
what helps a space vehicle re-enter the Earth’s atmosphere?
the surface of a space vehicle is made to withstand very hot temperature so it does not heat up at it re-enters the Earth’s atmosphere
