3 Physics - Motion, Matter, and Forces

Question 1

equation

speed

Answer 1

distance
________ = speed
time

Question 2

what is velocity?

Answer 2

speed in a given direction

Question 3

what does the gradient represent in a distance vs time graph?

Answer 3

the speed

Question 4

equation

acceleration

Answer 4

final velocity - initial velocity
______________________ = acceleration m/s^2
time

Question 5

in a speed vs time graph, how do you find the distance travelled?

Answer 5

it is the area under the line

Question 6

what is density?

Answer 6

the amount of matter in a given volume

Question 7

equation

density

Answer 7

mass
______ = density (g/cm^3 or g/ml^3)
volume

Question 8

describe and explain the 4 effects of force on objects

Answer 8

deformation - when a force changes shape of object

acceleration - unbalanced forces can cause an object to accelerate

oppose motion - friction and air resistance are examples of forces that make motion more difficult

upthrust - keeps objects from sinking in water & allows planes to fly

Question 9

what is newtons first law of motion?

Answer 9

mass resists motion
an object at rest will stay at rest, unless acted upon by an unbalanced force
an object at a constant velocity remains so, unless acted upon an unbalaced force

Question 10

unit of force

Answer 10

newtons (N)

Question 11

what happens if opposite forces are balanced/unbalanced?

Answer 11

if they are balanced it stays at constant speed

if it is unbalanced it accelerates

Question 12

what is resultant force?

Answer 12

if you have 20N acting to the right and 15N acting to the left, you have 5N of resultant force to the right

Question 13

what is limit of proportionality/hooke’s law?

Answer 13

http://www.mindset.co.za/resources//0000022668/0000029750/0000029690/da000215__110249.jpg

Question 14

equation for force?

Answer 14

f = mass x acceleration

Question 15

what is pressure dependent on?

Answer 15

force and area

Question 16

what is the unit of pressure?

Answer 16

N/m^2

Question 17

what is equation for pressure?

Answer 17

force
_____ = pressure
area

Question 18

why is it safer to lay down on ice than to stand on ice?

Answer 18

because you have the same force but when you lay down you have a greater area, which means that the force is more spread out, and there is less pressure so the ice is less likely to break

Question 19

why does a knife have a sharp edge?

Answer 19

it makes the area to which the force is being applied smaller, increasing pressure, making it easier to cut

Question 20

how does a tractor’s big tyres stop it sinking too far into soft soil?

Answer 20

the big area spreads out the weight, decreasing pressure