Chapter 4 Forces in Action Flashcards
What is the equation for force?
Force = Mass x Acceleration
What is the equation to find weight?
Weight = Mass x Force of gravity
What is weight?
It is the amount of Newtons of force that the earth is attracting the object
What is the centre of mass?
This is the position at which all the mass of an object appears to be
What is the centre of gravity?
This is the position at which all the weight of the objecct appears to be
What is the method / experiment to find the centre of gravity?
- Hang the object from a point that is off centre
- Draw a line vertically down from the point. Use a guide to help you know where to draw the line (e.g. a weight on a string).
- Repeat steps 1 and 2 until all the points cross at one point. This point is the centre of gravity
Name some important forces that can act on an object
Weight Friction Drag Tension Upthrust Normal contact force
What is a free-body diagram?
It is a diagram that isolates and shows all the forces acting on an object
What are the two factors that affect the drag force of an object?
The speed and the cross-sectional area
What is terminal velocity?
This is when the force of the weight moving the object through a fluid is equal to the drag force exerted on the object
What is a moment?
This is turning force of an object
What is the equation of a moment?
Moment = Force x perpendicular distance of the line of action of force from axis or point of rotation
What is the principle of moments?
When in equilibrium, the magnitude of the clockwise force is equal to the magnitude of the anticlockwise force
What is a couple?
This is the pair of forces acting on an object that rotates around a pivot point. The two forces must be parallel and along different lines.
What is the equation for a couple?
Moment = (F1 x d/2) + (F2 x d/2)
or if F1 and F2 are equal
Moment = F x d