4.7.1 Forces and Motion Flashcards
What is Displacement?
The straight line distance between a start and end point
What type of quantity is distance?
Scalar
Define a vector quantity.
A quantity with magnitude and direction.
How do you calculate speed?
Speed = Distance/Time
What does a straight diagonal line show on a DT graph?
Constant Speed
What does the area under a VT graph show?
Distance Travelled
What is typical walking speed?
1.5 m/s
What is typical running speed?
3 m/s
What is typical cycling speed?
6 m/s
How would you describe the velocity of an object in circular motion?
Velocity of an object in circular motion is constantly changing
What three things does the size of centripetal force depend on?
Speed, Mass, Radius of Circle
What are the units of acceleration?
m/s^2
What does a straight diagonal line show on a VT graph?
Constant acceleration
What is Newton’s First Law?
If the resultant force on an object is zero, it will continue to move in the same direction at the same velocity
What is Newton’s Second Law?
Acceleration is proportional to the resultant force acting on an object, and is inversely proportional to mass.
What is Newton’s Third Law?
Every action force has an equal and opposite reaction force
What is the equation for Kinetic Energy?
KE = 0.5 x mass x velocity^2
What is Inertia?
The tendency of object to continue in their state of rest or of uniform motion
What is the equation for Momentum?
Momentum(p) = mass(m) x velocity(v)
What is the law of Conservation of Momentum?
In a closed system, the total momentum before an event is equal to the total momentum after the event
How is Stopping Distance calculated?
Braking distance + Thinking Distance
What factors can affect thinking distance?
Tiredness, Drugs, Alcohol, Distractions
What factors can affect Braking distance?
Wet or Icy weather, poor road conditions, poor car conditions
How is the relationship between velocity and stopping distance?
As velocity increases so does braking distance
What energy transfer occurs when a car brakes?
Kinetic energy -> Thermal Energy
What does the gradient of a DT graph show?
Speed
How is the gradient of a curved line of best fit calculated at a specific point?
A tangent is drawn and the gradient is calculated
How does Centripetal force act on an object?
Centripetal force acts inwards
What is air resistance?
A force of friction produced when an object moves through the air
How is change in velocity calculated?
Change in Velocity = Final Velocity - Starting Velocity
State the equation linking Change in velocity, acceleration and distance.
Change in Velocity^2 = 2 x Acceleration x Distance
What does a negative change in velocity show?
Deceleration
What is terminal velocity?
The maximum speed of an object travelling
Describe the forces acting on an object at terminal velocity.
The forces are balanced
Identify the main energy transfer of an object as it falls.
Gravitational potential energy -> Kinetic Energy
How does a parachute decrease terminal velocity?
The parachute increases air resistance, causing deceleration. When the forces become balanced, the terminal velocity is lower
Identify the Gravitational Field Strength of Earth.
9.8 N/kg
What force prevents an apple from falling to the ground?
Tension of the stalk
According to Newton’s 1st, what is needed to make an object accelerate?
An overall resultant force applied to the object
Identify the equation linking Force, mass and acceleration.
Force = Mass x Acceleration
How can acceleration be measured more accurately?
Using a light gate to reduce random error from human measurement
If a ball impacts a solid desk with 10N of force, how much force is exerted on the ball?
10N (Newton’s 3rd Law)
Identify the range of average human reaction time.
0.3 - 0.9s
What two forces are acting on a falling object?
Weight/Gravity, Air resistance
In what direction does centripetal force act?
Inwards
True or false: Centripetal force can only be supplied by a contact force.
False: This can be a contact or Non-contact force i.e Gravity
How would a stationary object look on a DT graph?
Flat line
What does a flat line show on a VT graph?
Constant speed
How are acceleration and mass related?
Acceleration is inversely proportional to mass
What are the units of kinetic energy?
Joules (J)
