General Physics (Forces, Pressure etc) Flashcards
What is pressure the result of?
A force acting on an area
What is the equation for pressure?
P=F/A
What are the units for pressure?
N/m^2 or Pascal
Give 2 examples of pressure in everyday life
Clicking a button
Walking, as your shoes apply pressure to the ground
How would you get a small pressure?
Spread the force over a large area
How would you get a large pressure?
Spread the force on a small, concentrated area
Does pressure increase or decrease with depth?
Increase
What direction does pressure act in?
All directions
What angle does pressure act at?
Right angles (90o)
Why do liquids transmit pressure?
Because their molecules are free to move about
What is another equation for pressure? (Think boats)
P=hgp (P is pressure, h is height from surface, g is gravitational potential and p is density of the liquid
Give 2 examples of where a hydraulic jack is used
1) Trolley jack
2) Earth mover
What does the moment (turning effect) of a force rely on?
It’s size and position
What is the equation for moments?
Distance x force = moment
What is the unit for moments?
NewtonMetres (Nm)
What does the principal for moments state?
Clockwise moments = anti-clockwise moments
What can moments of a force be increased by?
-increasing force applied
What is the weight of an object called?
The Load
What is the force someone applies called?
The effort
What are other terms for the turning point?
The pivot or the fulcrum
What are some examples of energy?
Chemical, kinetic, gravitational potential, elastic potential, electrical, thermal, light, sound and nuclear,
What is work?
A quantity involving a force moving through a distance
What is the equation for work done?
Force x distance = work done
What unit is work measured in?
Joules
What is energy?
The ability to do work
What is gravitational potential energy?
The energy an object has due to it’s position above earth
What is the equation for gravitational potential energy?
GPE = m x g x h
What is kinetic energy?
The energy an object has due to it’s movement
What is the equation for kinetic energy?
KE = 0.5mv^2 (m is mass, v is velocity)
What is elastic potential energy?
The energy an object has because of it’s change in shape or displacement of it’s molecules
What does Hooke’s Law state?
As you add weights onto a spring, the spring will extend by and equal length each time a new weight is added on
What does the Law of the Conservation of Energy state?
Energy can neither be created nor destroyed, it can ONLY be transferred into other forms
Give some examples of energy transfers
- A torch, chemical energy gets converted to electrical energy which then transfers to heat and light energy
- A pendulum, GPE to KE to GPE to KE to GPE and so on
What is power?
The rate of doing work or transferring energy
What is the equation for power?
Power = work done/time taken
What are the units for power?
Watts
What is efficiency?
How useful/unuseful an energy transfer is
What is the equation for efficiency?
(Useful output/total input) x100
What is the equation for momentum?
M = kg x m/s
What is the conservation of momentum?
Momentum before = momentum after
What is another equation for force?
F=M x DeltaV/T
What is centripetal force?
A circular motion of an object around a point
When does centripetal force take place?
When the speed is constant
What is Boyle’s law?
Pressure and volume before = pressure and volume after
What is Brownian Motion?
The random ‘jiggling’ or motion of small particles
