P5-Forces Flashcards
What do vectors have?
Magnitude and direction.
What quantity is force?
A vector quantity.
What are lots of physical quantities?
Vector quantities.
Give examples of vector quantities?
Force, velocity, displacement, acceleration, momentum, etc.
Describe scalar quantities?
Only have magnitude and no direction.
What are examples of scalar quantities?
Speed, distance, mass, temperature, time, etc.
How are vectors normally represented?
An arrow showing the length of its magnitude.
And the direction showing the direction of the quantity.
What is a force?
A push or pull on an object that is caused by it interacting with something.
What is a contact force?
When two objects have to be touching for a force to act.
Give examples of contact friction?
Friction, air resistance, tension in ropes, normal contact force, etc.
What is a non-contact force?
If the objects do not need to be touching for the force to act.
Give examples of non-contact forces?
Magnetic forces, gravitational force, electrostatic force.
What is gravitational force?
The force of attraction between masses.
What is the difference between mass and weight?
Mass is just the amount of ‘stuff’ in an object. Where as weight is the force acting on an object due to gravity.
Why does gravitational field strength vary?
Because of the location. It’s stronger the closer you are to the mass causing the field, and stronger for larger masses.
What does the weight of an object depend on?
The strength of the gravitational field at a location of the object. Meaning the weight of an object changes with its location.
What is a resultant force?
The overall force on a point or object.
What happens when a force moves an object through a distance?
Energy is transferred and work is done on the object.
What is the conversion for joules to newton metres?
1J = 1Nm
How do you use scale drawings?
1) Draw the forces acting on an object, to scale, ‘tip-to-top’.
2) Draw a straight line from the start of the 1st force to the end of the 2nd - this is the resultant force.
3) Measure the length of the resultant force on the diagram to find the magnitude. And the angle to find the force’s direction.
When is an object in Equilibrium?
When the forces on it are balanced.
What elasticity movements transfer energy?
Stretching, compressing or bending.
When is work done in terms of elasticity?
When a force stretches or compresses an object and causes energy to be transferred to the elastic potential energy store of the object.
How is extension linked to force?
Extension is directly proportional to force. But this stops working when the force is great enough.
What quantity is speed and velocity?
Speed is scalar. Velocity is a vector.
What is the difference between speed and velocity?
Speed and velocity are both how fast you are. But velocity gives the direction as well.
What is acceleration?
Change in velocity in a certain amount of time.
What is uniform acceleration?
Speeding up or down at a constant rate.
What happens to drag when speed increases?
Drag increases.
What is drag?
The resistance you get in a fluid (gas/liquid). Air resistance is a type of drag.
What is the most important factor in reducing drag?
Keeping the shape of the object streamlined.
What does terminal velocity depend on?
Shape and area.
What is Newton’s first law?
Says that a resultant force is needed to make something start moving, speed up or slow down.
What will a non-zero resultant force always do?
Always produce acceleration (or deceleration) in the direction of the force.
What is inertia?
The tendency for motion to remain unchanged.
What does Newton’s third law say?
When two objects interact, the forces they exert on each other are equal and opposite.
What is the stopping distance equation?
Thinking distance + braking distance.
Thinking distance is affected by?
Your speed
Your reaction time.
What is braking distance affected by?
Your speed.
The weather/road surface.
Condition of tyres.
Brakes quality.
What does braking rely on?
Friction between the brakes and wheels.
Equation for momentum?
Mass x velocity.
What is conservation of momentum?
In a closed system, the total momentum before an event is the same as after the event.
