P5: Forces (triple) Flashcards
What is a vector?
A quantity with magnitude and direction.
What is a scalar quantity?
A quantity with magnitude.
What is a contact force?
When two objects have to be touching for a force to act.
What is a non-contact force?
When the objects don’t need to be touching for the force to act.
What is mass?
The amount of the object
It doesn’t change ever
What is weight?
The force acting on an object due to gravity.
What is the centre of mass of an object?
Where the force (weight) is pulling down on the object. It is usually the centre.
What is a free body diagram?
It describes all the forces acting on an isolated object describing the forces as arrows. The longer the arrow the greater the force.
What is the resultant force on an object?
The overall force acting on an object.
When is an object in equilibrium?
When the forces on it are balanced.
What is meant by an object that can be elastically deformed?
It goes back to its original shape after a force has been removed.
What is meant by an object being inelastically deformed?
When an object doesn’t return back to its original size a force has been removed.
What is the typical speed of a person walking?
1.5 m/s
What is the typical speed of a person running?
3 m/s
What is the typical speed of a person cycling?
6 m/s
What is the typical speed of a car?
25 m/s
What is the typical speed of a train?
30 m/s
What is the typical speed of a plane?
250 m/s
How do you find the distance travelled using a velocity-time graph?
The area under the graph.
How is acceleration shown on a free body diagram?
On arrow is bigger than the other.
What is inertia?
The tendency for motion to remain unchanged.
Stopping distance =
Thinking distance + braking distance
What is thinking distance effected by?
Speed
Reaction time
What is braking distance affected by?
Speed
Weather/road surface
Condition of tyre
Quality of brakes
Moment =
Force * distance
What is a moment?
The turning effect of a force.
What are the functions of gears?
to transmit rotational effects
why does the pressure of liquids increase as the depth increases?
the weight of the greater number of particles above a point pushes down on the point increasing the pressure
What is upthrust?
the force exerted onto the bottom of an object when submerged in a fluid due to the fluid’s pressure
How does upthrust have an upwards resultant force?
the pressure of a fluid increases with depth so more force is exerted on the bottom of the object creating an upthrust
What happens to an object in a fluid that has an equal weight being displaced and upthrust?
it will float
What is air resistance?
the frictional force produced by air acting ona moving objects.
