Physics Answers

An unclothed person whose body has a surface area of 1.40m^2 with emissivity of 0.85 has a skin temperature of 37°C and stands in a 20°C room. How much energy does the person lose per minute?

Ten kilograms of steam at 100°C is condensed is 500 kg of water at 40.0°C. What is the resulting temperature?

How much heat is required to change 10 g of ice at exactly 0°C to steam at 100°C.

Determine the amount of heat required to boil a 20L of water. How much heat is needed to convert it completely into steam.

(a) A straight conducting wire is placed perpendicularly to the earth

magnetic field at a location. The earth magnetic field at the location has a

magnitude of 0.450 G. Determine the current that must flow in the wire for a

9.50 cm length of the wire to experience a magnetic force of 1.50 N due to the

earth magnetic field.

[1 T = 104 G]

(b) A wire of length 1.0 m carries a current of 1.0 A. The wire is formed into a

circular coil and the circular coil has one turn only. Determine the magnitude of

the maximum torque which is developed on the coil if it is placed in magnetic

field of 2.0 T.

How many seconds would it take for a 4.50kw motor to raise a 175.kg boiler to a height of 15.0m?

(a) the displacement x, in m, from the equilibrium position of a particle moving with simple harmonic motion, is given by, x= 0.05 sin 6t, where t is the time, in s, measured from an instant when x= 0. (1) state the amplitude of the oscillations. (2) calculate the time period of the oscillations and the maximum acceleration of the particle.

(b) A mass hanging from a spring-suspended vertically is displaced a small amount and released. By considering the force on the mass at the instant when the mass is released, show that the motion is simple harmonic and derive an expression for the time period. Assume that the spring obeys Hooke's law.

A wire with a mass of 64 g and 1 m long floats horizontally in magnetic field. If

B = 1.6x10^-2 T is at the direction perpendicular to the wire, calculate the value of current in the wire with the aid of a diagram.

a particle moving with SHM has a speed of 8.0ms^-1 and an acceleration of 12ms^-2 when its is 3.0m from its equilibrium position. Find : (a) the amplitude of the motion, (b) the maximum velocity, (c) the maximum acceleration.

a particle moves with shm of period 4.0s and amplitude 4.0m. its displacement from the equilibrium position is x. find the time taken for it to travel: (a) from x=4.0m to x= 3.0m, (b) from x=-4.0m to x=3.0m, (c) from x=0 to x=3.0m, (d) from x=1.0 to x= 3.0m.