Flash card for class 7

Density (ρ)

ρ = Mass ÷ Volume
ρ = m / V

Relative Density

R.D. = Density of substance ÷ Density of water

Relative Density (in masses)

R.D. = Mass of a substance ÷ ( Mass of same volume of water at 4⁰C )

Speed

Speed = Distance ÷ Time
v = d / t

Weight

W = Mass × g

Weight on Earth (in terms of Moon)

Wₑ = 6 × Wₘ

Area

Area = Length × Breadth
A = l × b

Volume

Volume = Length × Breadth × Height
V = l × b × h

Average Speed

Average Speed = Total Distance ÷ Total Time

Kinetic Energy (KE)

KE = 1/2 × Mass × Velocity²
KE = ½ m v²

Potential Energy (PE)

PE = Mass × g × Height
PE = m g h

Plane Mirror: Object-Image

Distance of object (u) = Distance of image (v)
Image is virtual and laterally inverted