Forces, Energy and Power

Question 1

Energy equations

Answer 1

Ew=Fd
Ep=mgh
Ek=1/2mv^2

Question 2

how to work out horizontal and vertical components of force acting on a box

Answer 2

SOHCAHTOA
Fh=Fcos theta (cos across)
Fv=Fsin theta (sin up)

Question 3

how to work out components of force down a slope

Answer 3

• component of weight acting down slope = mgsin theta

- component of weight acting normal to the slope = mgcos theta

Question 4

what happens if the angle increases on a slope

Answer 4

bigger angle –> Fh increases –> acceleration down slope increases

Question 5

balanced forces

Answer 5

equal in magnitude but opposite in direction

Question 6

how to work out friction

Answer 6

Fun=Fh-friction

Question 7

Ek at ground=

Answer 7

Ep at max height (h=v^2/2g)

Question 8

if a rope or cable is pulled tight…

Answer 8

there will be tension in the rope

Question 9

if no angle, tension=

Answer 9

Weight

Question 10

tension depends only on the…

Answer 10

mass it is pulling

Question 11

what happens to tension as angle increases?

Answer 11

tension increases because the horizontal component increases and the vertical component remains the same

Question 12

equation to work out tension at angles

Answer 12

cos theta = W/T (z angles)

Question 13

what is power?

Answer 13

the rate at which energy is transferred

Question 14

what is work done?

Answer 14

a measure of the energy transferred/converted during a process

Question 15

friction

Answer 15

the force that opposes the motion of all objects

Question 16

what does a scale in a lift read?

Answer 16

the upward force

Question 17

in what cases will apparent weight increase?

Answer 17

accelerating up and decelerating down

Question 18

in what cases will apparent weight decrease?

Answer 18

decelerating up and accelerating down.