Forces Flashcards
Define Inertia.
The reluctance of a body to change its state of motion.
Define mass.
The quantity of matter in the body. Measured in kg.
What is the relationship between mass and inertia?
The higher the mass, the larger the inertia.
What is the equation used to work out linear momentum? State its units.
Momentum (kg.m.s-1) = mass x velocity
Define what a force is.
The pushing or pulling action that one object exerts on another.
The force of 1N produces an acceleration of what in a 1kg mass?
1 m/s2
What is Newton’s 1st Law?
An object will remain at rest or continue to move at a constant velocity, unless acted on by a net, unbalanced force.
If forces are equal = no motion.
What is Newton’s 2nd Law?
The rate of change of momentum of a body is proportional to the force causing it and the change takes place in the direction in which the force acts.
F = ma (remember equation).
What is Newton’s 3rd Law?
For every action force, there is a reaction force which is equal in magnitude but opposite in direction.
Is force a vector or scalar quantity?
Vector: has a direction and magnitude.
Define weight and how it is calculated.
Force due to gravity.
Weight = mass x g (9.81)
Drag is an external force. What components are needed in order to calculate drag?
- Density of the fluid (air, water).
- Speed of the object relative to the fluid.
- Cross-sectional area.
- Drag coefficient.
When must drag be calculated and when can it be ignored in sports?
Drag is minimal in exercises such as walking and can hence be ignored.
Drag is usually calculated in sports such as cycling or motorsports.
What does friction do and how do we calculate it?
Friction limits sliding and rolling on a surface.
It can be calculated by F = uR.
u = Coefficient of friction. R = Normal reaction force.
What is ground force reaction (GFR)?
The force applied by the ground to the body.
