Physics Answers

At temperature of 20 degree Celsius, the length of a copper rod is 30 cm with a mass of 250g .Ravi heats up the copper rod by supplying 5 kJ of heat .Determine the length of the rod(in cm) after being heated.

if the speed of an observer v is added to the speed of light c, the resultant speed will be equal to :

(a) v+c

(b) v-c

(c) c

(d) v

The maximum kinetic energy of emitted photoelectrons in a photoelectric cell is 7.5X10-19 J. What is the stopping 

A car is moving in rest with an acceleration of 2 ms-2 and reached to 20ms-1. Find the time taken?

At what position of the pendulum is the potential energy maximum?what is the kinetic energy at this point?

When the direction of current is from negative to positive terminal of the battery then emf (E) is taken as

(a) positive

(b) negative

(c) zero

(d) normal?

A narrow coil of 10 turns and area 4×10^-2m^2 is placed in a uniform magnetic field of flux density of 10^-2T so that the flux links the turns normally .calculate the accurate induced EMF in the coil if it is removed completely from the field in 0.55seconds

A 200 g whistle firecracker is set and fired horizontally in a straight line on top a smooth platform.

Its speed is 1.654 m/s in 0.35 seconds.

a) What is the momentum ?

b) The force in that time.

From 12 m/s to 54 km/hr , a 1500 kg jeepney accelerates that produce a force of 450 N. Find

a) the momentum of the jeepney.

b) the time to accelerate ?

Internal critical angle in core at core cladding interface of a step index fiber 78.6. The refractive index of cladding is 1.45 what is refractive index of core