Newton Mechanics Flashcards
Acceleration, a
The rate of change of velocity with respect to time.
Newton’s First Law
A body stays at restcor continues to movr with a constant speed in a straight line unless a net external force acts on it.
Newton’s Second Law
The rate of change of momentum of a body is proportional to the resultant force acting on it and occurs in the direction of the force.
Newton’s Third Law
If body A exerts a force on body B, then body B exerts an equal but opposite force on body A.
Linear Momentum
The product of the mass of an object and its velocity.
p=mv
Impulse
Impulse of a force is the product of the average force and the time interval over which it is applied.
J=F dt =dp
Impulse is the area under the force-time graph.
Force, F
The rate of change of momentum.
Principle of Conservation of Momentum
The total linear momentum of a system remains unchanged if no net external force acts on the system.
Couple
A couple consists of a pair of parallel forces of equal magnitude but opposite direction whose lines of action do not coincide.
Moment of a Force
The moment of a force about a point is the product of the force with the perpendicular distance of the force from that point.
Torque of a Couple, τ
The torque of a couple is the product of one of the forces with the perpendicular separation between the couple.
Head-on collision
A type of collision in which the directions of motion before and after the collisiom are along the same line of motion.
RSOA RSOS
For elastic collion, RSOA=RSOS
u1-u2=v2-v1
(take note of sign convention, assume known velocity is positive)
100% KE is conserved!
Same final velocity
Perfectly inelastic collision
Use one variable v to represent the final velocity
Condition for translational equilibrium
The net external force acting on the body is zero.
Moment of a force
The moment of a force about a point is the product of the force and the perpendicular distance of the line of action of the force to the point.
Condition for rotational equilibrium
The net moment on the body about any point is zero
Principle of moments
For a body to be in rotational equilibrium,
Sum of CWM about any point= Sum of ACWM about the same point
Conditions for static equilibrium
The net external force acting on the body us zero.
The net torque on the body about any point is zero
Three-force system
When an object is in equilibrium, all the 3 forces acting on the object should intersect at a common point
Couple
A pair of forces which are equal inmagnitude but opposite in direction, whose lines of action do not coincide.
Torque of a couple
Is tge product if tge perpendicular distance between the lines of action of the forces and the magnitude of one if the forces.
Principle of floatation
Weight of fluid displaced= weight of the obejct
ps Upthust = weight of the fluid displaced, when the body is floating, then U=W of liquid displaced=W of object
Upthrust
Net upward dorce exerted by a fluid on a body fully or partially submerged in the fluid
