Equations

Question 1

What is the equation for weight?

Answer 1

Weight (N) = mass (kg) x gravity (10m/s² or 10N/kg)

W = mg

Question 2

What is the equation for average speed?
(Distance and time is known)

Answer 2

average speed (m/s) = distance (m) / time (s)

s = d / t

Question 3

What is the equation for average velocity?
(Displacement and time is known)

Answer 3

average velocity (m/s) = displacement (m) / time (s)

v = d / t

Question 4

What is the equation for acceleration?

Answer 4

acceleration (m/s²) = (final velocity (m/s) – initial velocity (m/s)) / time (s)

a = (v – u) / t

Question 5

What is the equation for average speed?
(Distance and speed are not known)

Answer 5

average speed (m/s) = (initial speed (m/s) + final speed (m/s)) / 2

s = (u + v) / 2

Question 6

What is the equation for average velocity?

Answer 6

average velocity (m/s) = (initial velocity (m/s) + final velocity (m/s)) / 2

V = (u + v) / 2

Question 7

What is the equation for Newton’s Second Law?

Answer 7

resultant force (N) = mass (kg) x acceleration (m/s²)

F = ma

Question 8

What is the equation for the Principle of Moments?

Answer 8

(When in equilibrium)

total clockwise moments (Nm) = total anticlockwise moments (Nm)

CM = ACM

Question 9

What is the equation for Hooke’s Law?

Answer 9

(Given that the limit of proportionality is not exceeded)

Force (N) = spring constant (N/cm) x extension (cm)

F = ke

Question 10

What is the equation for moments?

Answer 10

moment (N) = force (N) x perpendicular distance from the pivot (m)

M = Fd

Question 11

What is the equation for pressure?

Answer 11

Pressure (N/m²) = Force (N) / area (m²)

P = F / a

Question 12

What is the equation for efficiency?

Answer 12

efficiency (No unit) = useful output energy (J) / total input energy (J)

E = O / I

Question 13

What are the equations that describe the proportionality of acceleration to resultant force and the inverse proportionality of acceleration to the mass?

Answer 13

Acceleration is proportional to resultant force
Acceleration is inversely proportional to mass

a ∝ F[res]
a ∝ 1 / mass

Question 14

What is the equation for gravitational potential energy?

Answer 14

gravitational potential energy (J) = mass (kg) x gravity (10N/kg) x height (m)

Eₚ = mgh

Question 15

What is the equation for kinetic energy?

Answer 15

kinetic energy (J) = 1/2 x mass (kg) x velocity squared (m/s)

Eₖ = 1/2 x m x v²