Forces and motion Flashcards

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1
Q

What is a vector quantity

A

Forces that have a magnitude and a direction

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2
Q

Examples of vector quantities

A

Force,velocity,acceleration,momentum

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3
Q

What is a scalar quantity

A

Quantities with a magnitude but no direction

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4
Q

Scalar quantity examples

A

Speed distance mass temperature

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5
Q

What is a contact force

A

When 2 objects have to be touching for a force to act

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6
Q

Examples of contact force

A

Air resistance

Tension in ropes

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7
Q

What is non contact force

A

When two objects do not need to touch for a force to apply

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8
Q

Examples of non contact forces

A

Magnetic force

Gravitational force

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9
Q

What is the difference between mass and weight

A

Mass is just the amount off stuff in an object while weight is the force acting on an object due to gravity

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10
Q

What is the equation for weight

A

Weight = mass x gravitational field strength

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11
Q

What is resultant force

A

If you have a number of forces acting at a single point you can replace it with a single force .

This single force is called the resultant force

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12
Q

What is the work done equation

A

Force x distance

Energy transferred is the same as work done

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13
Q

What is the equation that links force and spring constant

A

Force=spring constant x extension

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14
Q

What is the equation for elastic potential energy

A

Elastic potential energy = 0.5 x spring constant x extension2

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15
Q

What is a moment

A

A moment is the turning effect of a force

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16
Q

What is the equation of a moment

A

Moment = force x distance

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17
Q

What is the equation for pressure

A

Pressure = force/area

18
Q

What is density the measure of

A

Measure of compactness of a substance i.e how close the particles in the substance are

19
Q

How do you calculate pressure at a certain depth

A

Height of the column x gravitational field strength x density of liquid

20
Q

What do objects experience when in a liquid

A

They experience upthrust

When the object is submerged the pressure of the fluid exerts a force from every direction

21
Q

Why does an object balance

A

When the upthrust is equal to the objects weight

22
Q

What happens when an object is denser than the liquid it is placed in ?

A

It is unable to displace enough fluid to equal it’s weight meaning it’s weight larger than the upthrust causing to to sink

23
Q

What is atmospheric pressure

A

The layer of air that surrounds the earth

24
Q

Why does atmospheric pressure decreases as we increase altitude

A

Atmosphere gets less dense so there are fewer air molecules

25
Q

Why is displacement a vector quantity

A

Measures the distance and direction in a straight line from an objects starting point to finishing point

26
Q

What is acceleration and how is it calculated

A

Acceleration is the change in velocity over a period of time

Change in velocity divided by time

27
Q

What is the equation that links final velocity and initial velocity

A

Final velocity 2 - initial velocity 2=2(acceleration x distance)

28
Q

What is drag

A

The resistance you get in fluids (gas or liquids)

For example air resistance is a drag

29
Q

How does an object reach terminal velocity

A

When an object first sets off the force of gravity is much more than the frictional force slowing it down so it accelerates . Over time these 2 forces will begin to balance out . (Acceleration force=frictional force) this causes an object to reach it’s maximum speed
(Terminal velocity)

30
Q

What does newtons first law state

A

A resultant force is needed to make something start moving , speed up or slow down .

31
Q

How do you calculate resultant force

A

force =Mass x acceleration

32
Q

What is inertia

A

Until acted upon objects that are stationery will remain that way and objects at a steady speed will also remain that way . The same state of motion is called inertia

33
Q

How do you calculate inertia

A

Mass = force / acceleration

34
Q

What is newtons third law

A

When 2 objects interact the forces they exert on each other are equal and opposite

35
Q

How do you calculate stopping distance

A

Thinking distance + braking distance

36
Q

Name factors that effect braking distance

A

Weather or road surface
Condition of tyres
Condition of brakes

37
Q

Energy transfer when when the brake pedal is pushed

A

When the brake pads are onto the wheels friction occurs
This causes work to be done ,the work done between the brakes and the wheels transfer energy from the kinetic energy stores in the wheels to the thermal stores of the brakes . This causes the brakes to increase in temperature

38
Q

Equation for momentum

A

Mass x velocity

39
Q

What is the conservation of momentum

A

In a closed system the total momentum before an event is the same after the event

40
Q

What is the equation for change in momentum

A

Force = change in momentum/change in time

41
Q

What safety features do cars have that help in a crash

A

Crumple zones-crumple on impact increasing the time it takes for the car to stop

Seat belts-stretch increasing the time taken for the wearer to stop

Air bags - inflate before you hit the dash board of a car, the compressing air inside it slows you down more gradually

42
Q

Newtons second law

A

Acceleration of an object depends on the mass of the object and the amount of force applied