Forces and Motion Flashcards
Explain what is meant by a scalar quanitity
a magnitude - can be described with a single numerical value
What are 2 examples of scalar quantities?
distance, speed, time, mass, energy
Explain what is meant by a vector quantity
a magnitude and direction
What are 2 examples of vector quantities?
force, velocity, displacement, momentum, moment
How do you calculate speed from a distance-time graph?
the gradient
What is the equation linking distance moved, time taken and average speed
speed = distance / time
What is meant by acceleration?
the change in velocity per unit time
What is the equation linking acceleration, change in velocity and time taken?
acceleration = change in velocity / time taken
How do you calculate acceleration from a velocity-time graph?
gradient
Which property of a velocity-time graph can be used to calculate the distance travelled?
area under the graph
State the equation linking final speed, initial speed, acceleration and distance travelled
final speed^2 = initial speed^2 + (2 * acceleration * distance travelled)
Name two forces which always oppose motion
Friction, Air Resistance (drag)
What force holds planets around the sun?
gravitational
What force holds electrons around the nucleus?
electrostatic
State how a force can affect the body that it applied on
shape, speed, direction it is moving
What is newtons second law?
F = ma (a resultant force means acceleration)
What is newtons first law?
balanced forces mean no change in velocity - if it is stationary it will stay still, if it is moving it will carry on at the same velocity
What is newtons third law?
if object A exerts a force on object B, then object B exerts an equal and opposite force on object A
What is the relationship between stopping distance, braking distance and thinking distance
stopping distance = braking distance + thinking distance
State 4 factors that affect the stopping distance of a car
reaction time, inital speed, road conditions, tire conditions, weather conditions, driver’s conditions, mass of the car
State two factors that affect air resistance on a falling object
surface area, speed
How does a falling object reach terminal velocity?
Object falls as a result of its weight, as it accelerates air resistance opposes the motion, therefore, resultant force decreases and since F=ma acceleration decreases
What is Hooke’s law?
Extension is directly proportional to the force applied
What is elastic behaviour?
an object recovers its original shape when the forces causing the extension are removed
What is plastic behaviour?
there is a permenant deformation to the shape of the object when forces are removed
