SP2 Flashcards

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1
Q

How do you work out the resultant force of 2 forces?

A

If the forces are acting in same direction, add them

If they’re acting in opposite directions, subtract one from the other

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2
Q

When is an object balanced?

A

When the resultant of all forces on an object is 0

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3
Q

When is an object unbalanced?

A

When there is a non-zero resultant for e on an object

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4
Q

What is Newton’s first law?

A

A moving object will continue to move at the same speed and direction unless an external force acts on it

A stationary object will remain st rest unless an external force acts on it

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5
Q

Do balanced forces change the velocity of an object?

A

No they don’t.

Unbalanced forces will change the speed and/or direction of an object

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6
Q

What happens if an object is moving in a circle?

A

It has a changing velocity even though it’s speed isn’t changing

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7
Q

What is centripetal force?

A

It is the resultant force that causes the change in direction
It acts towards the centre of the circle

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8
Q

What is mass?

A

Mass is the quantity of matter there is on an object and only changes if the object itself changes

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9
Q

What is weight?

A

Weight is a measure of the pull of gravity on an object and depends on the strength of gravity

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10
Q

What is the gravitational field strength on earth?

A

10 Newton’s per kilogram

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11
Q

Why is the formula for weight?

A

Weight = mass x gravitational field strength

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12
Q

What is Newton’s second law?

A

The acceleration in the direction of a resultant force depends on:

The size of the force
The mass of the object

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13
Q

How do you calculate the force on an object?

A

Force = mass (kg) x acceleration

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14
Q

Why is inertial mass?

A

Inertial mass = force on it /acceleration the force produces

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15
Q

What is Newton’s third law?

A

About the forces on 2 different objects when they interact. It can happen:

When objects touch
At a distance

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16
Q

What are action reaction forces?

A

Pie of forces acting on the 2 interactive objects

Forces always same size and opposite directions

17
Q

What is an equilibrium situation?

A

Nothing moves

18
Q

What is the difference between action reaction forces and balanced forces?

A

Action reaction forces act on different objects

Balance forces all act on the same object

19
Q

What happens to the action reaction forces when they collide?

A

Same size during collisions but don’t necessarily have same effect on 2 objects a the objects have different masses

20
Q

What is momentum?

A

Measure of tendency of an object to keep moving

21
Q

How is momentum calculated?

A

Momentum = mass x velocity

22
Q

How can force also be calculated?

A

Force = mass x change in velocity/time

Force = change in momentum/time

23
Q

What happens to the momentum of an object when it collides?

What’s it called?

A

Momentum of both objects is same before the collision as after, as long as there is no external forces acting.

Conservation of momentum

24
Q

What is thinking distance?

A

When you travel some distance while the driver reacts to the situation

25
Q

What is braking distance?

A

Go some distance further while the brakes are working to bring it to halt

26
Q

How do you work out the stopping distance?

A

Stopping distance= thinking distance + braking distance

27
Q

What can effect car brakes?

A

If they’re worn, they create less friction and not slow down as effectively
Road is wet or loose gravel, less friction so increase braking distance
Vehicle has more mass, more force needed to decelerate it so heavier vehicle may travel further

28
Q

How do you work out the energy transferred/work done?

A

Work done = force x distance moved in the direction of force

29
Q

What is kinetic energy and how is it calculated?

A

Energy stored in a moving object

Kinetic energy = 1/2 x mass x (speed) 2

30
Q

What happens to the kinetic energy when the vehicle stops?

A

The kinetic energy is transferred to other energy stores by the braking force

31
Q

What link is there between kinetic energy and work done?

A

Kinetic energy = work done

32
Q

What are crumple zones?

A

Built at the front of cars so the declaration and force of car is less as it takes a little time for this crumpling to happen