Chapter 2 Equations

Question 1

final velocity after acceleration (given the time taken)

uniform motion only

Answer 1

final velocity = initial velocity + acceleration × time

v = u + at

Question 2

displacement (given the acceleration)

uniform motion only

Answer 2

s = ut + 1/2 at^2

Question 3

What does ‘s’ stand for?

Answer 3

displacement

Question 4

Force (general)

Answer 4

F = ma

Question 5

Work done

Answer 5

W = f(s)

(force × displacement in the direction of the force)

(SEE NOTES)

Question 6

Frictional force - static friction

Answer 6

F ≤ μs × R

Frictional force ≤ coefficient of static friction × normal force

Question 7

displacement (given the velocity)

uniform motion only

Answer 7

s = ((v+u)t)/2

Question 8

Final velocity after acceleration (given displacement)

uniform motion only

Answer 8

v^2 = u^2 + 2as

final velocity squared = initial velocity squared + 2 × acceleration × displacement

Question 9

Frictional force - dynamic friction

Answer 9

F = μd × R

Frictional force = coefficient of dynamic friction × normal force

Question 10

Kinetic energy

Answer 10

1/2 mv^2

Question 11

Elastic potential energy

Answer 11

1/2 k(Δx)^2

x = extension, k = spring constant

Question 12

Gravitational potential energy

Answer 12

mgΔh

Question 13

Power

Answer 13

Fv (force x velocity)

or W/t (F*s/t)

Question 14

Efficiency (work)

Answer 14

Useful work out/total work in

Question 15

Efficiency (power)

Answer 15

Useful power out/total power in

Question 16

Momentum

Answer 16

p = mv (momentum = mass x velocity)

Question 17

Resultant force due to momentum

Answer 17

Δp/Δt

Question 18

Kinetic energy (given momentum)

Answer 18

p^2/2m

Question 19

Impulse

Answer 19

FΔt

or

Δp