Summary Notes - Topic 1 Forces and Motion - Edexcel Physics IGCSE Flashcards
What is speed defined as?
Distance travelled per unit time.
What does it mean if the speed of something is changing?
It is accelerating or decelerating.
What is the acceleration of free fall near to the Earth?
Constant.
What is the formula for average speed?
Average speed = total distance / total time.
How is velocity defined?
Speed in a given direction.
What is the definition of acceleration?
Change in velocity per unit time.
What is the formula for acceleration?
Acceleration = change in velocity / time taken.
What does the equation (final speed)² = (initial speed)² + (2 × acceleration × distance) represent?
A kinematic equation relating speed, acceleration, and distance.
What units are used for distance, time, speed, velocity, and acceleration?
- Distance: metres (m) * Time: seconds (s) * Speed/Velocity: metres per second (m/s) * Acceleration: metres per second squared (m/s²)
In a displacement-time graph, what does a horizontal line indicate?
The object is stationary.
What does a negative gradient in a displacement-time graph indicate?
The object is returning back to the starting point.
In a velocity-time graph, what does the gradient represent?
Acceleration.
What does a curved line in a velocity-time graph indicate?
The acceleration is changing.
What is a vector?
A quantity that has both magnitude and direction.
What is a scalar?
A quantity that has only magnitude.
Give examples of scalars.
- Distance * Speed * Time * Energy
Give examples of vectors.
- Displacement * Velocity * Acceleration * Force
What can forces change in a body?
- Speed * Shape * Direction
What is friction?
A force between two surfaces that impedes motion and results in heating.
What is Newton’s first law?
An object has a constant velocity unless acted on by a resultant force.
What is Newton’s second law?
Force = mass × acceleration (F = ma).
What does Newton’s third law state?
Every action force has an equal and opposite reaction force.
How is weight defined?
Weight is a gravitational force acting on a mass.
What is the formula for weight?
Weight = mass × gravitational field strength (W = mg).
What is the gravitational field strength on Earth?
10 N/kg.
What is terminal velocity?
The constant speed reached when the force of gravity is balanced by air resistance.
What factors increase thinking distance?
- Greater speed * Slower reaction time due to alcohol, tiredness, or distractions.
What factors increase braking distance?
- Greater speed or mass * Poor road conditions (icy, wet) * Poor car conditions (worn tires, worn brake pads)
What is stopping distance?
The sum of thinking distance and braking distance.
What is elastic deformation?
When an object returns to its original shape after the load is removed.
What does Hooke’s law state?
For a spring, F = kx, where F is the force, k is the spring constant, and x is the extension.
What is the limit of proportionality?
The point beyond which a material no longer obeys Hooke’s law.
What is the formula for moment?
Moment = force × perpendicular distance from the pivot (moment = Fd).
What condition must be met for an object to be in equilibrium?
The sum of clockwise moments equals the sum of anticlockwise moments.
What is momentum?
The product of mass and velocity (momentum = mass × velocity, p = mv).
How is force related to momentum?
Force = change in momentum / time taken.
What is the principle of conservation of momentum?
The total momentum before a collision is equal to the total momentum after the collision.
In a collision involving a gun and bullet, what is the total momentum before firing?
Zero.
What is the recoil speed of a gun if a 10kg stationary gun fires a 0.01kg bullet at 100m/s?
-0.1 m/s.
