p2 forces Flashcards

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1
Q

how can we measure speed if we know the distance

A

stop watch, light gate or ultrasound

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2
Q

what is the equation for average speed

A

speed = distance / time

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3
Q

what is speed measured in

A

metres per second

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4
Q

what is the difference between a vector and a scalar

A

a vector has a magnitude and a direction a scalar has a magnitude and no direction

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5
Q

name an example of a scalar and a vector

A

vector = force

scalar = time

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6
Q

what is the difference between distance and displacement

A

displacement is how far away you are from a point distance is how far the object has moved

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7
Q

what is the difference between speed and velocity

A

speed is a scalar, it has no direction eg, 15 m/s velocity is a vector it has a direction eg 15 m/s south

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8
Q

what is the cyclists total displacment on this velocity time graph

A
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9
Q

how do you work out distance / displacement on a velocity time graph

A

work out the area under the line

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10
Q

what is the equation of motion

A

final velocity - initial veloctiy = 2 X acceleration X distance

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11
Q

work this out

A

use the suvat equation (final velocity squared = initial velocity squared = 2 X acceleration X distance

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12
Q

whats the equation for kinetic energy

A

kinetic energy = 0.5 X mass X (speed)^2

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13
Q

what is newtons 3rd law

A

for every action there is and equal and opposite reaction

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14
Q

what is the diffence between contact and non contact forces

A

non contact - some objectss interact with eachother without making contact

contact - is any force that requires contact to cause an action

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15
Q

three examples of non-contact forces are………………………………………………………………………………………

A

electrostatic

magnetism

gravity

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16
Q

state one way gravity is different from magnetic and electrostatic forces

A

gravity only attracts, electrostatic and magnetic also repel

17
Q

what is a free body diagram

A

is a digram that show the forces acting on a single object

18
Q

explain how two focres of 10 N can have a resultant force of 0

A

they could be going in opposite directions

19
Q

what is newtons first law

A

an object will stay at rest or stay at the same speed uless a force acts upon it

20
Q

what is the principal of interia

A

the interia of an object measures how difficult it is to change its velocity

21
Q

explain how an object can move if it has a resultant force of 0

A

A moving object with a zero resultant force keeps moving at the same speed and in the same direction untill it is stopped

22
Q

explain why it is difficult to demonstrate newtons first law in a lab

A

because it is near impossible to not have some form of resistance going againt the object

23
Q

what is equilibrium

A

the when motion of an object doesn’t change

eg. a rock staying still or a ball rolling at a steady speed.

24
Q

what happens if the resultant force on an object is not zero

A

the speed of the object changes

the direction of object changes

25
Q

what is newtons seconf law

A

this law states that the acceleration that the resultant force produces depends on

size of the resultant force and the mass of the object

26
Q

what equation is used to work out inertia

A

force (N) = mass (Kg) X accelertion (M/S^2)

27
Q

on a roller coaster you do a loop-the-loop at a constant speed how can you be acclerating

A

well you are accelerating because velocity is a vector and as you go around the loop the direction you are traveling in is changing. the change in direction means that the velocity is changing therefor you are accelerating

28
Q

what is terminal velocity

A

this is when you stop accelerating as you fall as the air pressure is equal to that of the earth.

29
Q

what is momentum

A

it is a vector that depends on mass and velocity

30
Q

what is the equation for momentum

A

momentum (Kg/ms) = mass (Kg) X velocity (M/S)

31
Q

what is conservation of momentum

A

during a collision the momentums stays the same before and after the collision. this is the law of conservation of mass.

32
Q

what happens when objects collide

A

in theory all the kinetic energy get passed from one to the other. for examle if a red snooker ball hits a blue snooker ball, the ball snooker ball will begin to move with the same velocity.

this is often not the case as some energy is transfered to heat or sound energy

33
Q

how do you calculate work done

A

work done (J) = force (N) X