Forces & Motion

• A force is a push, pull or a twist that can cause an object to speed up, slow down, change direction or shape (accelerate).
• Force is measured in newtons (N) ex:weight,friction.
• Acceleration is a measure of how quickly an object's speed or direction of motion changes (m/s2) The result of a net force.
• Increase force - increase acceleration — Increase mass - decrease acceleration.
• Mass: The amount of matter in an object (measured in kg) is a constant for any given object.
• Weight: A force due to gravity will vary depending on gravitational acceleration (Earth: 9.8 m/s Moon: 1.8 m/s).
• Speed is the distance an object travels divided by the time it takes to travel that distance (m/s).
• Displacement: measures the change in a position of an object and its direction over a certain period of time.
• Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object's movement.
• Speed is scalar, velocity is vector.
• Scalar: Requires only magnitude.
• Vector: Requires magnitude and direction.
• Vector is represented by an arrow, and should be drawn to scale.
• Length shows magnitude, arrowhead shows direction.
• Motion Graphs (gradient) use distance - time gradient = speed and displacement - time velocity = displacement/time.
• The net force is all the forces acting on an object added together.
• NO NET FORCE=NO ACCELERATION.
• Law of Inertia: An object in motion (or at rest) will remain in motion (or at rest) unless acted on by a net force.
• Newton's Second Law: The acceleration of an object depends on the mass of the object and the amount of force applied (F=ma).
• Newton’s Third Law: For every action force, there is an equal but opposite reaction force.
• Instantaneous speed - speed at particular instant of time is represented by (v-u)/t.
• A = acceleration (m/s2) v= final speed ( m/s - end of acceleration) u= initial speed (m/s - before acceleration) t= time period of acceleration (s).
• v= final speed (m/s) u=initial speed (m/s) a= acceleration (m/s2) t= time (s).
• Distance - acceleration uses S= ut+1/2at2.
• F = ma Force = Newtons (N) Mass = kg Acceleration (m/s2).
• W = mg