P8: Forces Flashcards
What is a scalar quantity?
A quantity with magnitude only
What is a force?
A push or a pull that acts on an object due to the interaction with another object
What are 3 examples of contact forces?
Friction, air resistance and tension
What are 3 examples of non-contact forces?
Gravitational force, electrostatic force and magnetic force
What type of quantity is force?
A vector
What is weight?
The force acting on an object due to gravity
What is the formula for weight?
W = mg
What is the relationship between weight and mass?
They are directly proportional
What instrument is used to measure weight?
A calibrated spring balance
What is the resultant force?
The single force that has the same effect as all the original forces acting together
What is the equation for work done?
W = Fs (distance)
What is one joule equivalent to?
One newton meter
What is the moment?
The turning effect of a force
What is the equation for a moment? What is its unit?
M = Fd in Newton meters
What does Newton’s First Law state?
If the resultant force acting on a stationary object is 0, it will remain this way. Similarly, if the resultant force acting on a moving object is 0, it will move at the same velocity throughout
What is inertia?
The tendency of objects to continue in their state of rest/uniform motion
In a free body diagram of a plane, what do the arrows represent?
Upwards arrow = life, downwards arrow = weight, forwards arrow = thrust and backwards arrow = air resistance
What 2 properties might be affected by resultant force?
Speed and direction
How do you draw scale diagrams?
Put arrows tip to tail, and do pythagoras. To find the size, find the angle
How do you resolve a force?
Make a scale, then draw horizontal and vertical components of the line and measure with ruler. Ensure you change back to newtons
What do levers do?
They transmit the turning effect of a force
Which force in a lever is closer to the pivot?
Output, meaning a larger force
