Forces
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Scalar quantities only have …
Magnitude
Vector quantities have …
Magnitude and direction
In a vector quantity what does an arrow represent?
Length = size and direction shows direction.
What is a force?
A push or a pull that acts on an object due to the interaction with another object.
What are contact forces and examples?
When the objects are physically touching. Friction Air resistance Tension Normal contact force
What is a non-contact force and examples?
When the objects are physically separated. Gravitational force Electrostatic force Magnetic force
What is weight?
The force acting on an object due to gravity.
What are the typical values of speed for walking, running and cycling?
1.5, 3, 6
A runner runs around a circular track at a constant speed. Will her velocity be constant?
No as the direction is changing and velocity is a vector.
What does a horizontal line on a distance time graph show?
That the object is stationery.
What is acceleration?
The rate of change of velocity. (So whenever an object’s velocity changes an object is accelerating).
What is uniform motion?
An object that is stationary or has a constant velocity.
What is non-uniform motion?
An object with a changing velocity.
How do you find speed at an instant from a distance time graph showing acceleration?
Use a tangent.
How do you find distance from a velocity-time graph?
The area between the line and the x-axis.
What does a horizontal line represent?
DT - Stopped VT - constant velocity, not accelerating
What does a straight line with a constant gradient represent?
DT - constant velocity VT - Constant acceleration
What does the gradient tell us?
DT - velocity VT - acceleration
Is force a vector or scalar quantity?
Vector
From what point on an object can the force of weight be considered to act?
The centre of mass
What is a resultant force?
The combined effect of the forces acting on an object.
What is Newton’s first law?
Resultant forces cause acceleration.
What is gravitational field strength?
The number of newtons of weight per kilogram of mass at a point in a gravitational field.
What is tension?
An inwards pull from either end of a stretched object.