9i forces (physics)

Question 1

speed formula + mean speed formula

Answer 1

• speed = d/t (distance/time)
• units for speed are km/h or m/s or mph.
• mean speed = average speed (the total distance travelled/by the total time taken)

Question 2

how do you find relative speed?
e.g. a car travelling at 50km/h overtakes one travelling at 30km/h. find the relative speed.

Answer 2

• ans. = 20km/h
• to find the relative speed of two bodies moving in the same direction, find the difference between the speeds of the bodies.
• to find the relative speed of two bodies moving in opposite directions, add the speeds of the two bodies together.

Question 3

gradient definition + formula

Answer 3

• gradient = a measure of how steep the line is
• gradient = speed
• gradient = distance moved / time taken

Question 4

forces, moments definition + formula

Answer 4

• forces can be used to turn objects around pivots/fulcrum
• moment = a turning force
• **moment = force (N) x distance (m)
• **equilibrium = balanced moments

Question 5

force multipliers vs. distance multipliers (definitions)

Answer 5

• force multiplier = when you increase the force of the load (effort)
• distance multiplier = when you increase the distance that the load moves

Question 6

simple machines definition (give 3 examples)

Answer 6

simple machine = machines with a few or no moving parts used tp make work easier (changing the direction of the force or motion). Levers, ramps and pulleys are all simple machines

Question 7

work definition, work done definition + formula

Answer 7

• work = the amount of energy being transferred (Joules)
• work done = when a force moves through a distance
• work done (J) = force (N) x distance