Motion & Newton's Laws & Energy

Question 1

what is v

Answer 1

change in position over time (s/t)

Question 2

what is speed

Answer 2

how fast the distance is changing every sec

Question 3

what is acceleration

Answer 3

how fast the velocity is changing e.g. Vf-Vi/t

Question 4

what is s

Answer 4

straight line distance from start point to end point

s= ut + 1/2(at^2)

Question 5

what do vectors need

Answer 5

scalar & direction e.g. 15m <– = -15

Question 6

what is newton’s 1st law

Answer 6

silk table cloth - body will remain at rest / move with constant v unless acted on by a resultant force

Question 7

what is newton’s 2nd law

Answer 7

F = ma e.g. the resultant force on an object is equal to the rate of change of it’s momentum

Question 8

what is newton’s 3rd law

Answer 8

equal & opposite force

Question 9

what is the difference between driving & frictional forces

Answer 9

driving is pushing the object and is +ve, while frictional is resisting it and is -ve

Question 10

where do gravitational fields point

Answer 10

directly toward the centre of massw

Question 11

how is gravity measured (units)

Answer 11

N/kg or m/s2

Question 12

what is kinetic energy

Answer 12

E = 1/2(mv^2)

Question 13

what is gravitational energy

Answer 13

E = mgh

Question 14

what is work energy

Answer 14

W = Fs

Question 15

what is torque

Answer 15

tao (t) = Fr

Question 16

what are the principles of projectile motion

Answer 16

• symmetrical
• v = 0 at max height
• v for vertical component
• kinetic energy than gravitational energy

Question 17

what are the principles of circular motion

Answer 17

a = v^2/r
so F = m(v^2/r)
use trig to work out tension

Question 18

what is the formula for gravitational field strength on earth

Answer 18

g = (G x m)/r^2
where m = planet mass, r = distance from centre of mass

Question 19

what is the relationship between gravitational strength & distance r

Answer 19

being further away (big r) reduces g

Question 20

what is the relationship between r & F in torque

Answer 20

inverse, harder to push a door near it’s pivot point, easier further out

Question 21

what is the formula for elastic energy

Answer 21

E = 1/2* (kx^2)
where x = compression, k = spring constant (N/m)

Question 22

what is momentum and can newton’s 3rd law apply

Answer 22

p = m*v

yes

Question 23

what is the formula for impulse momentum

Answer 23

change in p = net F x change in t,

where p = pfinal - pinital
- so it can be -ve

Question 24

can net force be negative

Answer 24

yes when the object comes to a stop

Question 25

what is potential energy & it’s diff. to kinetic

Answer 25

energy stored by a field e.g. gravitational, electric or magnetic

e.g. not kinetic because these are particles moving around

Question 26

what happens when 2 gasses are heated to produce water, gas and energy e.g. CH4 + O2 –> H2O + CO2 + energy

Answer 26

greater PE –> lower PE, more KE and radiation

Question 27

is radiant energy (light/warmth) kinetic or potential?

Answer 27

both

Question 28

what is the formula for power

Answer 28

W/change in time

Question 29

what is the significance of gravitational fields for an object in free fall

Answer 29

acceleration = magnitude of gravity

Question 30

what is the formula for tension

Answer 30

a = sum of forces/mass of object

gravity is a negative forcce because tension is always pulling, while gravity is pushing

Question 31

explain horizontal & vertical vector components in projectile motion

Answer 31

horizontal component is constant and only determines how far the ball goes

vertical component changes and becomes shorter as it gets to the peak where gravity kicks in and it becomes 0. then it gets larger again

Question 32

what is the formula for vertical velocity

Answer 32

v = u + at