P8 Flashcards
(25 cards)
What is displacement?
Distance without change in direction.
What is a vector?
Physical quantities with size (magnitude) and direction.
What is a scalar?
Physical quantities with size but no direction.
What is weight?
Force of gravitational field on an object.
What is mass?
Amount of matter.
What is velocity?
Speed in a certain direction.
What is power?
Rate of change of energy.
What is force?
Push or pull that acts on an object.
What is the third law of motion
Every action has an equal and opposite reaction
What can a force cause an object to do?
Change shape (stretch or squash), change its motion (accelerate/decelerate), change its state of rest (start moving).
What is friction?
The force exerted by a surface against an object when it moves across it.
What does ‘every action has an equal and opposite reaction’ mean?
It describes Newton’s third law of motion.
What is a resultant force?
Single force that has the same effect as all the forces acting on the object.
What is a balanced force?
If the resultant force acting on an object is zero, all the forces are said to be balanced.
What is an unbalanced force?
If the resultant force acting on an object is not zero, all the forces are said to be unbalanced.
What is a moment?
Turning force around a fixed pivot.
How is moment calculated?
Moment = Force x Distance from pivot.
What are force multipliers?
They multiply the applied force allowing you to lift more for less work.
What is the role of gears?
Transfer force and change the moment of a turning effect.
How is moment calculated with gears?
Moment = Force x Gear radius.
What is the centre of mass?
Point at which its mass can be thought of as being concentrated.
How do you find the centre of mass for irregular objects?
We need a plumb line.
How to calculate a resultant force when forces are not opposing one another
Parallelogram of forces ( compass method )
What is a resolving force
The vertical and horizontal components of a force
