Forces Flashcards
What are Scalar Measurements
Measurements with only magnitude
What are Vector measurements
Measurements with magnitude and direction
Examples of Scalar Measurements
Speed, Distance, mass, temp. and time
Examples of Vector Measurements
Force,Velocity ,Displacement,acceleration and momentum
What is the equation that links speed,distance and time
Speed = Distance/time
What is the equation that links acceleration,change in distance and time
Acceleration = Change in distance/time
Define acceleration
Quantity that tells us how quickly an objects velocity is changing
Define Deceleration/Retardation
How quickly an objects velocity is decreasing
What does the gradient of a Distance/Time graph tell us
Tell us how fast the object is travelling and no gradient means it is stationary
What does the gradient of a Velocity/Time graph tell us
- Line going up shows acceleration
- Line going down shows retardation
- Flat gradient shows constant speed/stationary so 0 acceleration
How do you work out the acceleration from a velocity/time graph
You work out the gradient
How do you work out the distance travelled from a Velocity/Time graph
You work out the area of the graph
What is the equation that links weight,mass and gravitational field strength
Weight = mass * gravitational field strength
What is gravitational field strength (unless told explicitly to use another value)
g = 9.8 N/kg
How are forces represented in diagram
Forces are represented by arrows. The size of the arrow represents magnitude while direction shows direction of the force
What is the difference between mass and weight
Mass is substance measured in kg
Weight is the force objects experience due to gravity
How do you work out the resultant force
1) Add forces together
2) if resultant force is 0 the object will stay moving in that direction at constant speed
3) if resultant force is more than 0 it will accelerate in that direction
What is the equation for Pythagoras
a^2 + b^2 = c^2
What is terminal velocity
When an object falls and the 2 forces balance out over time
How do you work out diagrams when there is no angle involved
1) choose an appropriate scale
2) Draw a scaled diagram using ruler and protractor
3) to work out magnitude measure length of diagonal line and multiply length by scale
How do you work out diagrams when 2 components are perpendicular to each other
look at notes for example
What is Newtons 1st law
a stationary object stays stationary
a moving object continues to move at the same velocity unless enacted upon by an external force
What is Newtons 2nd law
Force= Mass*Acceleration
What is Newtons 3rd law
For every action there is an opposite and equal reaction this is why we don’t fall through a chair when we sit on it.
Define a contact force
-When 2 objects have to be touching for a force to act
Define a non-contact force
-When 2 objects don’t have to be touching
What is the equation that links force,spring constant and extension
Force= spring constant*extension
What are the units for spring constant
N/m
What are the units for acceleration
m/s/s or m/s^2
What is the equation that links kinetic energy,mass and velocity
KE = 0.5MassVelocity^2
What is the equation that links Gravity potential energy,mass,gravitational field strength and change in height
GPE= mass*g *change in height
What is the equation for efficiency
Useful Energy
Efficiency = ——————— * 100
Total Energy
Define Efficiency
How much energy we supply that is turned into useful energy
What is the equation that links Power,energy and time
Power(watts)= energy (j) / (time (s)
What is the equation that links work done,force and distance
• Work Done = Force*Distance
What is the equation that links momentum,mass and velocity
• Momentum (kgm/s) = mass * velocity
What is the unit for momentum
(kgm/s)
What is the Law of conservation of momentum
• When 2 or more objects collide, the total momentum conserved before and after is the same, so you add the momentum
What is the equation that links moment,force applied * distance to pivot
Moment= Force applied * distance to pivot (clockwise or anti)
What is the equation for stopping distance
Stopping distance = braking distance + thinking distance
Define centre of mass
the weight of an object can be considered to act at a single point
How do levers help use less force
• Levers increase the distance from the pivot from the pivot, this means less force is required to get the same moment
How do larger and smaller gears interact
- If a larger gear is driven by a smaller gear, the large gear will rotate slowly but will have a greater moment
- If a smaller gear is driven by a larger gear, the larger gear will rotate quickly but will have a smaller moment
Define pressure
how much force is acting on a given area. It is measured in a unit called pascals or Nm2
how does atmospheric pressure work
the pressure decreases as you go up and increases as you go down
How do our bodies deal with pressure
When pressure acts on a body, it has the same outward pressure from our body, so we aren’t squished.
What happens to out bodies as you go higher
When people go up and the atmospheric pressure decreases the pressure in our bodies is greater than the outward it causes internal damage and sickness.
What is the equation for pressure in liquids
• pressure = height of column (m) × density of the liquid × gravitational field strength
What is the equation for density
density= mass/volume
What is the equation for pressure
Pressure (Pascals) = force/area
What is the speed of sound
330m/s
How does weight and upthrust interact
When weight = upthrust an object floats, measured by the amount of water an object displaces. The size of the upthrust depends on the size of the object i.e. going into a bath
What do sankey diagrams show
the amount of chemical energy input turns into useful and wasteful energy
