P5 Forces Flashcards
What is the unit of force?
newton (N)
What is a resultant force?
The overall force on an object.
List four contact forces.
Normal contact force, friction, air resistance, tension.
List three non contact forces.
Magnetism, gravity, electrostatic.
What equation links, force, extension and spring constant?
Force = spring constant x extension
F = ke
If the elastic limit is not exceeded, what does a graph of force against extension for a spring look like?
Straight line through the origin.
Distance and displacement - which is a vector and which is a scalar?
Distance = scalar Displacement = vector
What’s the difference between speed and velocity?
Speed is a scalar, velocity is a vector.
What is the equation for speed?
Speed = distance/time
How do you calculate speed from a distance-time graph?
Gradient of graph = speed
What is the equation to calculate accceleration?
Acceleration = change in speed/time taken
How do you calculate acceleration fom a velocity-time graph?
Gradient of graph = acceleration
How can distance be calculated from a velocity- time graph?
Distance travelled is the area under the graph.
If an object has balanced forces acting on it. What happens?
A stationary object remains stationary, a moving object continues at the the same speed in the same direction.
What are the overall forces on an object at terminal velocity?
Zero, the forces are balanced.
What equation connects mass, force and acceleration?
Force = mass x acceleration
What is the elastic limit?
The point at which an object will no longer return to its original shape when any external forces are removed.
What is Newton’s Third Law?
For every action there is an equal and opposite reaction.
What is stopping distance?
Stopping distance = thinking distance + braking distance
List the factors affecting thinking distance.
Speed, tiredness, alcohol/drugs, distractions (e.g. mobile phones)
List the factors affecting braking distance.
Speed, brake condition, wet/icy roads, tyre condition.
What is the main energy transfer during braking?
Kinetic to thermal (heat)
What is centre of mass?
The point at which all of an object’s mass appears to be concentrated.
What is the equation for calculating weight?
Weight = mass x gravitational field strength
How is momentum calculated?
Momentum = mass x velocity
What is conservation of momentum?
The total momentum before a collision = the total momentum after the collision
Describe how the objects are moving in these distance time graphs.
A - stationery
B - constant speed away from start point
C - constant speed towards start point
D - accelerating
E - decelerating
F - constant speed but slower than B
