#### Work Done Against Friction and Gravity

to overcome this force. In general we can apply one of the equations: Energy Supplied=Increase in Kinetic Energy +Work Done Against Friction+Increase in Potential Energy where is the velocity, is the acceleration, is the resistive force and is the angle...

https://astarmathsandphysics.com/a-level-maths-notes/m1/3594-work-done-against-friction-and-gravity.html#### Back EMF in an Electric Motor

When an electric motor is running, current is used to turn the motor and provide movement. This movement is produced because current flowing in the coil while the current is in a magnetic field leads to a force on the arms of the coil, the direction of...

https://astarmathsandphysics.com/o-level-physics-notes/138-back-emf-in-an-electric-motor.html#### Conservation of Energy

The Principle of Conservation of energy is one of the most important principles in physics. It means that we don't have to assume that energy disappears into a black hole from which it cannot be recovered. If energy is still lost to friction or heat,...

https://astarmathsandphysics.com/o-level-physics-notes/146-conservation-of-energy.html#### The Observations of Count Rumford

did nothing to promote one. He referred to heat having been generated by friction but failed to grasp that work done against friction was used to heat the water.

https://astarmathsandphysics.com/o-level-physics-notes/267-the-observations-of-count-rumford.html#### Why Ice Is Slippery

effectiveness of this layer into doubt however. It is now believed that the reason for the film of water is the work done against friction by the skater as they move. Part of this work becomes internal energy of the ice, which melts.

https://astarmathsandphysics.com/o-level-physics-notes/299-why-ice-is-slippery.html#### Maximum Extension of Elastic String Attached to Particle on Rough Plane

stretched. The total initial energy is then zero. If the coefficient of friction is then the friction force The work done against friction in moving from A to B is then Conservation of energy then gives Expanding the brackets and collecting like terms...

https://astarmathsandphysics.com/a-level-maths-notes/m3/3642-maximum-extension-of-elastic-string-attached-to-particle-on-rough-plane.html#### Stopping Distance of a Trolley Experiment

Apparatus: Dynamics trolley, tape measure (or 2 x metre rulers), stop-clock, corridor Diagram: Procedure: 1. Gently push the trolley away from a known position on the corridor carpet so that it stops after about one metre. 2. Repeat the above but this...

https://astarmathsandphysics.com/a-level-physics-notes/experimental-physics/2726-stopping-distance-of-a-trolley-experiment.html#### Force and Power

One of the basic equations of physics is or If the work is done in a time then we can divide both sides by to obtain or where and We can generalise this equation: If a body is travelling at a velocity against a force then the power needed to overcome...

https://astarmathsandphysics.com/a-level-maths-notes/m2/3611-force-and-power.html#### Motion of Particle on Inner Surface of Smooth Sphere

A particle travelling on the inside surface of a smooth sphere will just leave the surface when the reaction between the particle and the inner surface is zero. Suppose a particle of mass at the bottom A of a sphere of radius r is given a horizontal...

https://astarmathsandphysics.com/a-level-maths-notes/m3/3644-motion-of-particle-on-inner-surface-of-smooth-sphere.html

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