Forces Flashcards
Newton’s 1st law
A body stays at rest or continues to move with a constant speed in a straight line unless acted upon by a net external force.
Newton’s 2nd law
The rate of change of linear momentum of a body is directly proportional to the resultant force acting on it and occurs in the direction of the force
Newton’s 3rd law
If body A exerts a force on body B, then body B will exert an equal and opposite force on body A
Linear momentum
Linear momentum of a body is the product of its mad and its velocity.
Impulse
The impulse of a force is the product of the average force and the time interval over which it is applied
Impulse-momentum theorem
The change in momentum of a particle during a time interval equals the impulse of the net force that acts on the particle during that interval
1 Newton
The amount of force that gives an acceleration of 1ms^-2 to a body with a mass of one kilogram
Principle of conservation of linear momentum
The total linear momentum of a system is conserved if no external force acts on the system
Head-on collision
One in which the directions of motion before and after the collision are along the same line of motion
Elastic collisions
KE is conserved, relative speed of approach = relative speed of separation
Inelastic collisions
KE not conserved
Perfectly inelastic collision
2 objects stick together and move with constant velocity. This represents the maximum possible loss of KE without violating the PCOE
Hooke’s law
The extension of a spring is proportional to the load if the limit of proportionality is not exceeded
Upthrust
The upward force acting on an object that is partially or fully immersed in a fluid, due to differences in pressure acting on the top and bottom face
Couple
Consists of a pair of parallel forces of equal magnitude but opposite direction whose line of action do not coincide.
Moment of a force
The product of the force with the perpendicular distance of the force from that point
Torque of couple
The product of one of the forces with the perpendicular separation between the couple
Archimedes’ principle
An object immersed fully or partially in a fluid experiences an upthrust equal to the magnitude of the weight of the fluid displaced
Rotational equilibrium
When there’s no resultant moment about any point
