Physics Answers

An elastic cord can be stretched to its elastic limit by a load of 2N. If a 35cm length of the cord is extended 0.6cm by a force of 0.5N what will be the length of the cord when the stretching force is 2.5N?

Car A of mass 3000 kg moving at 72km/hr, east tries to overtake the car B of mass 1250 kg moving at 60km/hr, east. Car A collides with car B. The cars stick together after the collision. Find their velocities after the collision. Note: The two cars are moving in the same direction.

5. An electron has a kinetic energy of 6.4 X 10^-19 J. What is this energy in electron volts?

6. Two metallic plates are 0.04 m apart and the potential difference between them is 50 V. Between the two equipotential surfaces, there is a potential difference of 2.5 V. Find the spacing in this part of the field between two metal plates.

3. Four point charges are placed at the four corners of a square that is 30 cm on each side. Two of the 4 charges are +2μC and two are -2μC. Find the potential at the center of the square.

4. The potential difference between two parallel plates of a condenser that are 4 mm apart is 800 V. What is the potential gradient?

A. If you do 12 J of work to push 0.001 C of charge from point A to point B in an electric field, what is the potential difference between points A and B?

B. What will be the increase in kinetic energy of an electron if it has been accelerated through a potential difference of 20 million volts? (Assume that e = 1.6 X 10^-19 C)

1. A 92 kg/s flow of steam enters a turbine at 100 bar, 774 K and a velocity of 35 m/s. The machine is well insulated and the steam leaves at 0.1 bar, 365 K and at a velocity of 350 m/s. Calculate the power output from the turbine and the inlet and outlet pipe diameters required assuming that steam is an ideal gas with Cp=1901 J/kg.K.

A copper cube with sides of length 40mm had its surface blackened.the cube is heated up to 500k and place inside a room at a constant temperature of 300k.calculate the initial rate of temperature fall of the cube, assuming it is a perfect blackbody.take SHC of aluminium to be 400j/kg/k, density of aluminium=7800kg/m3

Calculate the power in a 1000 Ω electric heater if the current through it is (a) 0.5 A & (b) 1A.

providing the given, required, formula,

solution/substitution of data

1. Calculate the resistance of a copper wire that is 3-meter long and has a diameter of 0.005m.

2. The resistance of a piece of carbon at 20⁰C is 10 Ω. What is its resistance at (a) 30⁰C &(b) 10⁰C?

providing the given, required, formula, solution/substitution of data,

Two charges lie on positive x-axis. Charge A (3.0 x 10^-9 C) is 3.0 cm from the origin and Charge B is 5.0 cm from the origin. (-4.0 x 10^-9 C). What is the total force exerted by these two charges on Charge C (6.0 x 10^-9 C) located at the origin?