5.2 Gravitational potential energy and kinetic energy

4 of 4 objectives have lessons · 0 studied · 0 secure

Lessons

Lifting things: turning work into stored energyLifting a mass at steady speed means pushing up with a force equal to its weight, so the work you do (Fs) becomes mgΔh of stored gravitational energy. 6 min, not started
Using ΔE_P = mgΔh without tripping upUse ΔE_P = mgΔh for lifts, drops and height changes, keep track of signs, and read the energy straight off a height graph. 6 min, not started
Where does ½mv² come from?Push a mass with a constant force over a distance and the work done equals the kinetic energy gained; the equations of motion turn that into E_K = ½mv². 7 min, not started
Using E_K = ½mv²: the squared bit that bitesKinetic energy grows with the square of speed, so doubling your speed quadruples the energy you must lose to stop — which is why stopping distances grow so fast. 6 min, not started
Falling, swinging and rolling: height becomes speedSet mgh equal to ½mv² to find the speed gained when something falls — the mass cancels, so heavy and light objects land at the same speed. 7 min, not started

4 objectives

What Cambridge says you should be able to do, in our words. Codes are the topic number plus the objective’s position.

5.2.1

Use W = Fs to derive ΔE_P = mgΔh for a change in gravitational potential energy in a uniform gravitational field.

Taught in: Lifting things: turning work into stored energy · 6 questions

5.2.2

Recall and use ΔE_P = mgΔh for a change in gravitational potential energy in a uniform gravitational field.

Taught in: Falling, swinging and rolling: height becomes speed, Using ΔE_P = mgΔh without tripping up · 12 questions

5.2.3

Use the equations of motion to derive the kinetic energy formula E_K = ½mv².

Taught in: Where does ½mv² come from? · 6 questions

5.2.4

Recall and use E_K = ½mv².

Taught in: Falling, swinging and rolling: height becomes speed, Using E_K = ½mv²: the squared bit that bites · 13 questions