Forces and Motion Flashcards
(26 cards)
Explain a distance time-graph?
Gradient gives the speed
Straight lines mean steady speed
Flat line mean stopped
Curves mean accelerating or decelerating
Formula for speed?
Distance/ time
Formula for acceleration?
change in velocity/ time
Explain a velocity-time graph?
Gradient means the acceleration of the object
Straight line means steady acceleration
Flat line means steady speed
Curves mean increasing or decreasing acceleration
How do you find the distance travelled on a velocity-time graph using area?
The distance travelled in any time interval is equal to the area under that section of the graph
What is the formula for final speed?
Final speed^2 = initial speed^2 + (2 * acceleration * distance)
v2 = u2 + (2 * a * s)
What can forces do?
Act on a body to change the velocity, speed, direction and shape
Identify all 7 forces?
1) Gravity/ weight
2) Reaction force
3) Electrostatic force
4) Thrust(push or pull)
5) Drag/ air resistance/ friction
6) Lift
7) Tension
What is a vector quantity?
Vector quantities have size and direction:
Force, velocity, acceleration, momentum
What is a scalar quantity?
Scalar quantities only have size:
Mass, temperature, time, length
What does friction oppose?
Motion
What is the formula for force?
Mass * acceleration
What is the formula for weight?
Mass * gravitational field strength
What makes up stopping distance?
Thinking distance + braking distance
What affects the stopping distance of a vehicle?
1) Speed
2) Reaction time
3) Mass
4) Brake quality
5) Surface condition
Why do falling objects reach terminal velocity?
1) When an object falls it has much more force accelerating it than resistance slowing it down
2) As its velocity increases, resistance builds up
3) This resistance force gradually reduces the acceleration until eventually the resistance force is equal to the accelerating force.
4) At this point the object wont be able to accelerate any more so it will reach terminal velocity
What is Hooke’s law?
How that extension is proportional to force
What happens when a spring is stretched past its elastic limit?
When a spring has too much force added it loses its ability to return
Once its past the elastic limit it will not return to its original length
What is the formula for momentum?
Mass * velocity
What is the relation ship with force, change in momentum and time taked?
Force = change in momentum/ time taken
What is Newtons first law?
Forces that are balanced will have no change in velocity
What is Newtons second law?
A resultant force will lead to acceleration
What is Newtons third law?
If object A exerts a force on object B then object B will exert a equal and opposite force on object A
What is the formula for a moment?
Force * perpendicular distance from the pivot
