p2 forces

Question 1

how can we measure speed if we know the distance

Answer 1

stop watch, light gate or ultrasound

Question 2

what is the equation for average speed

Answer 2

speed = distance / time

Question 3

what is speed measured in

Answer 3

metres per second

Question 4

what is the difference between a vector and a scalar

Answer 4

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

Question 5

name an example of a scalar and a vector

Answer 5

vector = force

scalar = time

Question 6

what is the difference between distance and displacement

Answer 6

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

Question 7

what is the difference between speed and velocity

Answer 7

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

Question 8

what is the cyclists total displacment on this velocity time graph

Answer 8

Question 9

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

Answer 9

work out the area under the line

Question 10

what is the equation of motion

Answer 10

final velocity - initial veloctiy = 2 X acceleration X distance

Question 11

work this out

Answer 11

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

Question 12

whats the equation for kinetic energy

Answer 12

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

Question 13

what is newtons 3rd law

Answer 13

for every action there is and equal and opposite reaction

Question 14

what is the diffence between contact and non contact forces

Answer 14

non contact - some objectss interact with eachother without making contact

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

Question 15

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

Answer 15

electrostatic

magnetism

gravity

Question 16

state one way gravity is different from magnetic and electrostatic forces

Answer 16

gravity only attracts, electrostatic and magnetic also repel

Question 17

what is a free body diagram

Answer 17

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

Question 18

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

Answer 18

they could be going in opposite directions

Question 19

what is newtons first law

Answer 19

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

Question 20

what is the principal of interia

Answer 20

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

Question 21

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

Answer 21

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

Question 22

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

Answer 22

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

Question 23

what is equilibrium

Answer 23

the when motion of an object doesn’t change

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

Question 24

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

Answer 24

the speed of the object changes

the direction of object changes

Question 25

what is newtons seconf law

Answer 25

this law states that the acceleration that the resultant force produces depends on size of the resultant force and the mass of the object

Question 26

what equation is used to work out inertia

Answer 26

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

Question 27

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

Answer 27

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

Question 28

what is terminal velocity

Answer 28

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

Question 29

what is momentum

Answer 29

it is a vector that depends on mass and velocity

Question 30

what is the equation for momentum

Answer 30

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

Question 31

what is conservation of momentum

Answer 31

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

Question 32

what happens when objects collide

Answer 32

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

Question 33

how do you calculate work done

Answer 33

work done (J) = force (N) X