P8 Forces in balance Flashcards
Scalar quantities have…
Magnitude but no direction
Vector quantities have…
Magnitude and direction
Examples of scalar quantities (6)
Distance, speed, time, mass, energy and power
Examples of vector quantities (5)
Displacement, velocity, force, weight and momentum
What is displacement?
Distance travelled in given direction
What is the unit of force?
Newtons (N)
Examples of contact forces (2)
Friction and air resistance
What is Newtons third law of motion?
When two objects interact with each other, they exert equal and opposite forces
What is the resultant force?
A single force that has the same effect as all the forces acting on an object
What happens to an object if the resultant force is zero?
The object stays at rest or stays at the same speed and direction
What happens to an object if the resultant force is greater than zero?
The speed or direction of the object will change
What does a free body force diagram show?
All of the forces acting on a single object
What is moment?
The turning effect of a force
What is the equation for moment?
Moment (Nm) = Force (N) x perpendicular distance to pivot (m)
How can you increase the size of the moment?
Increasing the magnitude of the force, increasing the perpendicular distance to the pivot
What is the force applied to a lever called?
The effort
Explain what a force multiplier is and give an example
Something that increases the amount of force that you can place of an object, for example a lever
What does a low gear do?
Gives a low speed and a high turning effect
What does a high gear do?
Gives a high speed and a low turning effect
What is the centre of mass of an object?
The point at which its mass can be thought of as being concentrated
Where is the centre of mass for a flat object that is symmetrical?
Along the axis of symmetry
What is the principle of moments?
The sum of the anticlockwise moments about any point = the sum of the clockwise moments about that point
What is a parallelogram of forces?
A scale diagram of two vectors that can be used to find their resultant
What does resolving a force mean?
Finding perpendicular components that have a resultant force that is equal to the force
What is the resultant force for an object in equilibrium?
Zero
