Physics Answers

1. A charged parallel plate with 15F connected to a battery with 9V. When a dielectric material was inserted between the parallel plates. What happens to the stored charges in the capacitor? 2. Find the capacitance of a layer of Al203 that is 0.5 m thick and 2000 mm2 of square area ( r= 8.854 x 10-12FM-1).

A system is comprised with multiple bodies. These bodies hold some charges. The charges are q1, q2, q3 and q4 and the value charges are +5C, +10C, -2C, -15C respectively. Find out the net charge on the system.

The temperature of 200 g of water decreases from 20 °C to 0 °C in 10 minutes. Calculate

i. the heat lost by the water.

ii. the rate at which the water is losing heat.

iii. the time taken for the water at 0 °C to turn completely into ice.

A constant net force of 350 N is applied to accelerate a cart in a frictionless surface from rest to a velocity of 65 m/s in 20 s. What is the mass of the cart?

The resistance of a uniform copper wire 50.0 meters long and 1.15mm in diameter is 0.830 ohms at 20°C. What is the resistivity if the copper at this temperature?

A 60kg survivor of a shipwreck sits on a block of wood having volume of 1.6m³. Two birds of the block of the wood is under seawater (density = 1025 kg/m³ .find a the volume of diaplaced seawater by the block of wood, b. buoyant force on the block of wood and the survivor

a bicycle wheel turns with constant angular accceleration of 0.64 rad/s²:

a) how much time does it take to reach an angular velocity of 8 rad/sec starting from rest?

b) how many revolutions does the wheel turn in this time interval?

1/. A signal is transmitted from a ship and an echo is received from an object below the ship 4 s later. Calculate the distance of the object from the ship if the speed of sound in water is 1400 m/s.

A proton is placed in a uniform electric field of 2.75 × 103 N/C. Calculate the

magnitude of the electric force felt by the proton. (The charge of a proton is

+1.6 × 10−19 C).