Physics Answers

A wire , 20m long is heated from a temperature of -5⁰c to 55⁰c,if the change in length is 0.020m, calculate the linear expansivity of the wire

A wire is Bent into a circle of radius a and a total charge Q is distributed uniformly around it.find the magnetic field at the center if the wire rotates with an angular velocity w about the axis of the circle

The electrical resistance of a platinum wire of zero degree celsius is 9.8 ohmes and 11.0 ohmes at 100 degree celsius. calculate the temperature when the resistance is 10.4 ohms assuming that the change in electrical resistance of the conductor is proportional to the change in temperature

If a line to ground fault occurs at the supply voltage causing a very high current of 500A, what is the new receiving end voltage at the car side

1. An object of mass 3kg is dropped from the roof of a two-storey house and reaches the ground with a speed 10 m/s. Neglecting friction, calculate:

i. The kinetic energy of the speed when it reaches to

the ground.

ii. The potentia energy of the object when it is on the

roof.

iii. The height of the roof

iv. The total mechanical energy of the object when it is

1 m above the ground.

2. A man who has a mass of 80 kg can run up a flight of stairs of 20 steps in 5 seconds. Given the each steps in 20cm high, how much power does the man use to run up the flights of stairs?

1. Estimate the volume of the earth in m3 by assuming that its radius is 6400km.

2. A car accelerates from zero to 20 m/s in 5 s.

i. Calculate the acceleration of the car.

ii. If acceleration is assumed to be constant, how far

will the car travel in 15 s?

iii. Calculate the speed of the car after 15 s.

3. A KTM Commuter train travel between two station, A and B. The train from rest from station A and accelerates at a constant rate for 0.5 k.m until it reaches a speed of 30 m/s. It then travel at this constant speed for Ts before decelerating at a constant rate of 1.5 m/s and coming to rest at station B. Determine the value of T if the distance between the two stations 6km. Calculate also the total time taken for the whole journey.

the inisial and final velocity of a body are (12 + or - 0.2) and (20 + or - 0.3) . find change in velocity

A woman weighing 75 kg stands on a spring scale in elevator. During the first 3 seconds of motion from rest, the tension T in the hoisting cable is 8300 N. The total mass of the elevator , woman scale is 750 kg.

1.Find the vertical acceleration of the elevator.

2.Find the reading R of the scale in Newtons during this interval.

3.Find the upward velocity of the elevator at the end of a 3 seconds.

What is difference between rotational kinetic energy and linear kinetic energy. Write down their formulas and compare them.

Two spherical masses of mass 2kg each are connected by a light thin rod of length 50cm. Calculate its rotational inertia:

a. about an axis normal to it through its centre

b. about an axis at one of it ends