Unit 1 Equations

Question 1

Average Speed

Answer 1

S = average speed (m/s)
d = distance (m)
t = time (s)

Average Speed = total distance
——————–
Total time

Question 2

Average Velocity

Answer 2

Displacement/Change in time

Question 3

Acceleration

Answer 3

a = (v - u) / t

u= initial velocity (m/s)
v = final velocity (m/s)
t = time (s)

Question 4

Average speed (velocity)

Answer 4

Average speed (velocity) = (u + v) / 2

u= initial speed (velocity) (m/s)
v = final speed (velocity) (m/s)

Question 5

Rate of change of speed

Answer 5

Rocos = (v - u) / t

ROCOS = (m/s2)
u= initial speed (m/s)
v = final speed (m/s)
t = time (s)

Question 6

Resultant force

Answer 6

F = ma

F = Resultant force /N
m = mass /kg
a = acceleration / m/s2

Question 7

Weight

Answer 7

W = m × g

W = weight /N
m = mass /kg
g = 10 N/kg

Question 8

Hookes Law

Answer 8

F = ke

F = force applied /N
k = spring constant N/cm or N/m
e = extension (stretched length - unstretched

Question 9

Pressure

Answer 9

F
P = —-
A

P = Pressure (1 N/m2 = 1 Pa)
F = force applied
A = cross-sectional area / m2 or cm2

Question 10

Moment of a force

Answer 10

M = F x d

M = moment / Ncm or Nm
F = Force applied /N
d = perpendicular distance between force and pivot / cm or m

Question 11

Principle of Moments

Answer 11

F1×D1 = F2×D2

CM = ACM

Question 12

Density

Answer 12

M
D = —–
V

d = density /kg/m3 or g/cm3

Question 13

Efficiency

Answer 13

Useful energy output
Efficiency = ——————————–
Total energy input

Question 14

Work done

Answer 14

w.d = F x d

w.d = work done /J
F = force applied /N
d = distance moved /m

Question 15

Power

Answer 15

E W
P = —– = ——
t t

P = Power /W
W = work done /J
E = Energy transferred /J
t = time /s

Question 16

Kinetic energy

Answer 16

1
KE = —– mv²
2

KE = kinetic energy /J
m = mass /kg
v = speed /m/s

Question 17

Gravitational potential energy

Answer 17

GPE = mgh

GPE = gravitational potential energy /J
m = mass /kg
h = height /m