Assistant engineer interview questions-1
“Conservation of energy sates that energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another” .
- Produce electricity from water :Water falls from the sky that will store in the dam .The potential energy of water in a dam can be turned into kinetic energy that energy will rotate the turbine and of a generator to produce electricity .
- Moving car hits on a parked car: Energy transferred from one system to another system .
- Pushing a book across the table
- Kicking ball that is sitting on the ground
Si unit of energy : Joules
1 Joule =1Kg.m^2s
Energy of motion
The kinetic energy of an object of mass m , moving with a velocity v is given by
K E =1/2mv^2
Here v is the speed of the particle
Example : Moving water
The energy of the location with respect to some reference point . In other words an object can store energy as the result of its position .
An object of mass m at a height h above the earth’s surface has a gravitational potential energy g
PE = mgh
Where g is the acceleration due to the earth’s gravity.
Example: An object falling towards earth
Electric energy is energy that is caused by moving electric charges. In other words energy created by separating charges .
- Energy stored in battery
- A lamp plugged into a wall outlet
How to produce the electric energy
1. Hydroelectric power plant
2. Nuclear Energy Power plant
- Water hammering
Water hammer is defined as the sudden increase in the pressure of water due to any obstruction or any direction change .
Cause of water hammer:Sudden closing of valve,Obstruction,Sudden bent
How to avoid the water hammer:To control the Pressure Variations, due to rapid changes in the pipeline flow
Methods to Avoid water hammer:Surge tank,Storage reservoir
Cavitation is formation of vapor bubbles in the liquid flowing through any Hydraulic Turbine. Cavitation occurs when the static pressure of the liquid falls below its vapor pressure.
How its affect hydroelectric power plant:The bubbles collapsing near the machine surface are more damaging and cause erosion on the surfaces called as cavitation erosion
How to avoid Cavitation:in design of any hydraulic system care should be such that at point of the path of the fluid pressure doesn’t fall below the vapor pressure of the fluid.