P2.2 Flashcards
What force opposes gravity?
The reaction force
What can a force do?
Change the shape of an object
Change an object’s motion
What do changes in motion include?
Being at rest (not moving) and acquiring a velocity
Travelling at a constant velocity and INCREASING in velocity
Travelling at a constant velocity and DECREASING in velocity
Travelling at a constant velocity and CHANGING DIRECTION
How can you represents forces in diagrams?
As arrows
What is the difference between the force of gravity and an electrostatic force?
The force of gravity is only attractive but an electrostatic force can be attractive or repulsive
What happens when 2 opposing forces are balanced?
You move at a constant (uniform) speed
What is a non-contact force?
When two object give rise to a force without touching, the forces that emerge are called non-contact forces
What is newtons 3rd law?
When two bodies interact, they exert a force upon each other that is equal in size, but opposite in direction
Why are tension and compression similar?
Compression is the force acting opposite to tension
What is a free body diagram?
A diagram that shows all the forces acting on a single body
What is the meaning of forces acting in the horizontal plane?
If two forces act left and right
What is the meaning of forces acting the vertical plane?
If two forces act up and down
What is resultant force?
The total force of forces that act in the sample plane
How can you find resultant force?
By adding or subtracting two forces acting on the same plane
How do you work out the resultant force of two forces that aren’t on the same plane?
You connect them making a triangle and use pythagorus’s theorem or trigonometry to find the hypotenuse which is the resultant force
What is Newton’s 2nd law?
The acceleration experienced by a body is directly proportional to the resultant force acting upon it and in the same direction as it.
How do we know if the body is accelerating?
If the speed and/or direction of motion change
What is the formula for resultant force when we don’t know the forces?
Mass (Kg) x acceleration (m/s^2)
What is the formula for acceleration?
Final velocity (m/s) - initial velocity (m/s)
———————————————————
Time (seconds)
What is the centripetal force?
When an object is constantly accelerating and so must be subject to a resultant force
What does the centripetal force do?
It always acts towards the centre of the circle and acts only the change the direction of the velocity (not the size).
What is terminal velocity?
When the forces on you are are equal and your motion no longer changes
What is momentum and why do you need to be careful when doing calculation?
It is a vector so you need to take account of direction
What is the formula for momentum?
Mass (Kg) x velocity (m/s)
How do you calculate velocity of two bodies after a collision using momentum?
You find the total momentum before the collision
That total momentum would equal the total mass of the bodies multiplied by the momentum after. Meaning you would do:
Momentum before
—————————-
Total mass
To give the velocity of the two trolleys after
What is the equation for work done?
Force (N) x Distance (M)
What are the units for work done?
Joules
What is 1 newton-metre the same as?
1 joule
How do you calculate power?
Work done (J)
———————
Time (s)
What are the units for power?
Watts
What is work in science?
It is about using forces to transfer energy between stores
What are joules equal to?
1 Joule = 1 newton-metre
What is power?
The rate at which energy is transferred
What is the formula for power?
Work done (J)
———————
Time (s)
What are the units for power?
Watts
