Forces Flashcards
What is a force?
> It is a push or Pull factor, that acts on an object due to its interaction with another object.
What is a contact force and give some examples?
> Requires two objects to be touching.
E.g. Friction, air resistance, Tension
What is a non-contact force and give some examples?
> Doesn’t require objects to be touching.
E.g. Gravitational, electrostatic, magnetic
What is a scalar quantity with examples?
> Have only magnitude
E.g. speed, mass, distance, temperature, time
What is a vector quantity with examples?
> It has magnitude and direction
E.g. Displacement,momentum,velocity,ecceleration,force
What is the resultant force?
> Resultant Force=Overall force on an object
Equilibrium is all forces=0
What is Elastic deformation
When an object returns to its original shape.
What is inelastic deformation?
> When an objects stays deformed.
What is Extension?
Increase in length of a spring when its stretched.
What is the formula which involved Force,spring and extension?
F=Ke
Force = Spring X Extension
(N) (N/m) (M)
What is Hooke’s Law?
Force is Directly Proportional to Extension
How do you workout Elastic Potential Energy?
Ee = 0.5 k e^2
Elastic Potential Energy = 0.5 X Sprung constant X Extension^2
Describe a method used to investigate the stretching of a Spring?
- Set up a clamp stand with a clam and hang the spring from the clamp
*Use a second clamp and boss to fix a (half) metre rule alongside the spring
*Record the ruler reading that is level with the bottom of the spring
*Hang a 1 N / a known weight from the bottom of the spring
*Record the new position of the bottom of the spring
*Calculate the extension of the spring and measure the extension of the spring
*Add further weights to the spring so the force increases 1 N at a
time up to 5 N
Formula to workout velocity?
Displacement
Velocity = ————————-
Time Taken
Typical Everyday speeds?
Walking=1.5 m/s
Cycling=6 m/s
Running=3 m/s
Train=5 m/s
Car=25 m/s
Train=55 m/s
What is acceleration?
> Rate of change in velocity.
(How quickly something speeds up/slows down).
What is the equation for acceleration?
. . . Change in Velocity (m/s)
Acceleration= ————————————–
Time (s)
What is the equation for acceleration?
2as= v’2-u’2
2(Acceleration + Distance) = Final V - Initial V
Describe the terminal velocity of objects falling?
> At the start when they fall off, the force of gravity is much more than the frictional force, so they accelerate.
As the speed increases friction builds up
This gradually decreases the acceleration until eventually the frictional force is equal to the accelerating force
It will have reached it’s maximum speed
Describe the terminal velocity of a skydiver falling?
> Initially, the upwards air resistance is very small because the skydiver isn’t falling very quickly
As they speed up, the air resistance increases, eventually growing large enough to balance the downwards weight force
Once air resistance equals weight, there is no longer any resultant force
Therefore, the skydiver’s acceleration is zero - they now travel at a constant speed
This speed is called their terminal velocity
What is Newton’s First Law of Motion?
> ‘If the resultant force of a stationery object = 0, the object will remain stationery.
If the resultant force of a moving object is 0 then it will carry on moving at the same velocity’.
What is Newton’s second law of motion?
‘The larger the resultant force acting on an object, the more the object accelerates’.
What is the formula to workout force?
F=MA
Force= Mass X Acceleration
What is Inertia?
> The tendency for the motion of an object to remain unchanged.
