Page 236 - Class-11-Physics-Part-1_Neat

210 PHYSICS

Energy Power
1 kW h = 3.6 MJ 1 horsepower (hp) = 550 ft lbf/s
1 cal = 4.186 J = 745.7 W
–1
1ft lbf = 1.356 J = 1.286 × 10 –3 Btu 1 Btu min = 17.58 W
–3
1 L atm = 101.325 J 1 W = 1.341 × 10 hp
1 L atm = 24.217 cal = 0.7376 ft lbf/s
1 Btu = 778 ft lb = 252 cal = 1054.35 J Thermal Conductivity
–1 –1
2
1 eV = 1.602 × 10 –19 J 1 W m K = 6.938 Btu in/hft °F

2
2
1 u c = 931.50 MeV 1 Btu in/hft °F = 0.1441 W/m K
–7
1 erg = 10 J
APPENDIX A 5
MATHEMATICAL FORMULAE
Geometry y x
sin θ = cos θ =
Circle of radius r: circumference = 2πr; r r
area = πr 2 tan θ = y cot θ = x
2
Sphere of radius r: area = 4πr ; x y
r r
4 sec θ = csc θ =
volume = π r 3 x y
3
Right circular cylinder of radius r Pythagorean Theorem
2
and height h: area = 2π r +2π r h;
2
2
In this right triangle, a + b = c 2
volume = rπ 2 h ;
Triangle of base a and altitude h.
1
area = a h
2
Quadratic Formula
2
If ax + bx + c = 0,
2
− b ± b − 4ac
then x =
a 2
Trigonometric Functions of Angle θθ θθ θ Fig. A 5.2
Triangles
Angles are A, B, C

Opposite sides are a, b, c
Angles A + B + C = 180 0

sin A sin B sin C
= =
a b c
2 2 2
c = a + b – 2ab cos C
Fig. A 5.1 Exterior angle D = A + C

2018-19