Forces Flashcards
What is an external force ?
- Comes from outside the body
- E.g. friction, air resistance, weight, reaction force
What is an internal force ?
- A force produced by skeletal muscle
- E.g. contracting the quadriceps to extend the knee in a jump
What are two different types of vertical force known as ?
Weight
Reaction force
What is weight ?
Mass * acceleration
What is Reaction force ?
The force where two bodies are in contact with one another
E.g kicking a football
What is a horizontal force ?
Friction
What are the two types of frictional force ?
Static
Sliding
What is a static force ?
Friction between two surfaces with no movement
What is a sliding force ?
Friction between two surfaces when there is movement
E.g. curling
What are key areas which effect air resistance ?
- Higher velocity = higher air resistance
- The larger the area of body, the larger the air resistance
- Shape and characteristics determine air resistance
What is air resistance ?
A force that acts in the opposite direction to the motion of a body travelling through the air
How is weight force drawn on a free body diagram ?
Drawn downwards arrow from the centre of mass
How is the reaction force drawn on a free body diagram ?
Start from where the two bodies are in contact
How do you draw friction force on a free body diagram ?
- Starts where two bodies are in contact
- Opposite to potential slipping
- Drawn in same direction as motion
How do you draw air resistance on a free body diagram ?
Drawn from the centre of mass away from the direction of motion
What is netforce ?
Overall force on a body when all forces have been considered
What is a balanced force ?
When all forces acting on a body are equal
What is an unbalanced force ?
When a force acting in one direction is bigger than the force acting in the opposite direction
E.g Jumping in the air
What does it mean if friction and air resistance are equal ?
Someone is moving at a constant speed
What does it mean if friction is bigger than air resistance ?
Acceleration is happening
What does it mean if air resistance is bigger than friction ?
Deceleration is happening
