Formulae

Question 1

Formula of Weight

Answer 1

W = mg

Question 2

S.I. unit of speed

Answer 2

m/s

Question 3

S.I. unit of acceleration

Answer 3

m/s ^2

Question 4

S.I. unit of Force

Answer 4

kgms^-2

Question 5

Formula for Moment of a Force

Answer 5

1. T = Fd
T= Moment of a Force
F= Force
d= distance from the pivot. 
S.I. Unit = Nm

Question 5

Formula for Moment of a Force

Answer 5

1. T = Fd
T= Moment of a Force
F= Force
d= distance from the pivot. 
S.I. Unit = Nm

Question 6

Formula for Momentum

Answer 6

p = mv
p = Momentum
m = mass
v= velocity
S.I. Unit = kgm/s

Question 7

Formula for Momentum in Inelastic collision

Answer 7

(m1 v1 )+(m2 v2 ) = m1+m2 (v3 )Or (m1 v)+(m2v)

Question 8

Formula for Momentum in Elastic Collision

Answer 8

(m1 v1i) + (m2 v2i) = (m1 v1f) + (m2 v2f)

Question 9

Formula for Velocity

Answer 9

V= displacement / Time
v = s/t
V = u+at
Unit = m/s

Question 10

Formula for Acceleration

Answer 10

a = v-u/t

Unit - m/s

Question 11

Formula for Force

Answer 11

Force = Mass x acceleration
F=ma
Unit - Newtons

Question 12

Formula for the Area of a Triangle

Answer 12

1/2 base x height

Question 13

Area of a Rectangle

Answer 13

length x width

Question 14

Area of a trapezium

Answer 14

1/2 (the sum of the parallel sides) x height

Question 15

What is the Formula for extension?

Answer 15

Force = spring constant x extension
F=kx/ke
K unit = N/m
F unit = Newtons
e unit = metres

Question 16

Formula and Units for Work

Answer 16

Work = Force x Displacement
W = Fs
Units: Newton metre (Joul)
          N.m (J)
          foot pounds (horsepower)
          ft.lbs (Hp)

Question 17

Formula and Units for Power

Answer 17

Power = Work/time
P = Fs/t
P = Force x velocity

Units: Joule/second (J/s)
Watt (W)

Question 18

Formula and Units for Kinetic Energy

Answer 18

Kinetic Energy: energy due to motion; it reflects the mass and velocity of the object.

Units: (KE/Ek)
Formula: Ek = 1/2 mv^2

Question 19

Formula and Units for Potential Energy

Answer 19

PE/Ep
a) Gravitational Potential Energy - energy due to an object’s position relative to the Earth.

• affected by an object’s weight (W=mg)
• elevation (height) above reference point (ground or some other surface) (h)
• GEp = mgh

b) Strain/Elastic Energy: due to the deformation of an object

• bungee jumping
• stretching a tendon or ligament.

Question 20

Work-Energy Relationship

Answer 20

The work done by an external force acting on an object causes a change in the mechanical energy of the object.

Fs = change Energy
Fs = change Ek + Ep
Fs = 1/2 m(vf-vi)^2 +mg (rf-ri)