Mechanics Flashcards
a t u v
v = u + at
a s t u
s = ut + 1/2at^2
a s t v
s = vt - 1/2at^2
a s u v
v^2 = u^2 + 2as
s u t v
s = 1/2(u + v)t
If the net force is 0 the object is in?
Equilibrium - it stays stationary or at a constant velocity
The weight of an object is
mg - mass x 9.8
If an object is accelerating downwards, the net force is
Weight - Tension/up thrust etc. = ma
What force acts upwards at right angles to the region of contact?
Normal reaction/contact force
To resolve in the x direction
rNcosR
To resolve in y direction
rNsinR or rNcos(90-R)
What is the coefficient of friction and what does it usually lie between
Mu, between 0.3 and 0.9
What is limiting friction?
The greatest friction, just before an object is about to move.
F = mu x R
An object falling freely under the force of gravity has what acceleration?
9.8 m/s^2
An object projected upwards has what acceleration?
-9.8 m/s^2
When an object is projected upwards, peaks and begins to fall, what is the velocity at the peak?
0m/s
Equation for terminal velocity
R = kv or R = kv^2
If object A exerts a force on object B, what force does object B exert on A?
A force of the same magnitude in the opposite direction
When an object is in equilibrium, what are the forces equal to?
The upwards forces are equal to the weight.
The forces parallel to the plain are equal to each other.
When an object is about to lift off the ground, what is R equal to?
0
When are tension and friction on an object equal?
When it’s in equilibreum
What is the tension when two particles are attached by a light in extensible string?
It is equal, and acts in opposite directions
