IGCSE Science Revision

 When an object is stationary, it has an equal force pushing down and up, the downward force being gravity, and the upward force being normal contact force. e.g:  This object is stationary. When an object is accelerating, the forward force, the thrust - the motor or pedals of the vehicle, will be more powerful than the backwards opposing forces such as friction and drag. However, when an object is going at a constant speed, the forward and backward forces will be balanced, e.g: 6 N to 6 N. However, that object could just as easily be stationary as the forces will seem the same on a free-body diagram. During a collision, there is a change in momentum. The force (of the collision) = change in momentum / time taken. Car safety features such as seatbelts, air bags, and crumple zones all increase the time taken for the collision, meaning the force is then decreased. Whichever direction the force is greater in will be the direction the object travels in. In a collision between two b...

Momentum is defined as the product of mass and velocity. momentum = mass x velocity The units of momentum are kilogram metres per second - kg m/s As the velocity or mass increases, so does the momentum . Newton's laws of motion 1. An object will continue to stay at rest or at a steady speed unless a resultant force acts upon it. 2. When an unbalanced force acts on an object it accelerates. 3. Every action has an equal and opposite reaction. Terms you need to know mu = initial momentum mv = final momentum mv - mu / m(v - u) = change in momentum ∆ = the greek letter delta, representing 'change in' Rate of change of momentum Force (in N) = change in momentum (in kg m/s) / time (in seconds) Examples A tennis ball (0.3 kg) hits a raquet at 3 m/s and rebounds in the opposite direction at 6 m/s. What impulse is given to the ball? ∆ P (change in momentum) = m ( v - u)  = 0.3 ( -6 -3 )  = 2.7 kg m/s

 Hello everyone! This blog is dedicated to those of you struggling with the sciences or needing an extra push over your exam period - I will be uploading things topic by topic, starting with Physics! Hope you will find this useful!