## Submitted Questions

• #### Pawl Ratchet

How do pawl and ratchet works?

#### vinoythomas

• Mar 15th, 2010

A ratchet mechanism is based on a wheel that has teeth cut out of it and a pawl that follows as the wheel turns

• #### Power Consumed

If v=220V, I=25A, power factor=0.8, frequency=400Hz. If the motor runs for 3 hours, What is the power consumed?

#### bittu123

• Nov 10th, 2011

Calculating power, frequency and time is not required. P=V*I*Cos0 =220*25*0.8 =4400 watts answer But if you are looking for "How much energy motor consumed?" then you need time Energy consumed ...

#### dineshkumarsah.mj

• Jun 15th, 2011

Here Freq was given was wrong P V*I*CosAA is power factor V is VoltageI is Current P 220*25*0.8P 4400wattsPower P is 4.4Kwatts for one hour.For 3 hrs 4.4KW*3 = 13.2KW

• #### Diesel and Petrol Engines

Why diesel engines are called as high torque engines and petrol engines as high speed engines?

#### Sanjana0320

• Nov 12th, 2009

As diesel engine has high compression ratio therefore it has high torque. Petrol engines have high speeds coz it produces more heat at combustion chamber because of high calorific value moreover heat ...

• #### Resistance Force

A mass of 100kg is falling from a height of 1m and penetrates the sand to 1m. What is the resistance force of the sand?

#### Budi Joshi

• Mar 27th, 2015

Resistance Force=981N

#### Tarek

• Mar 3rd, 2015

Http://hyperphysics.phy-astr.gsu.edu/hbase/flobi.html

• #### Potential Voltage

Van de graff generator produces a voltage of 100,000 V but it does not harm us, where as, a 220V in wall outlet leads to death, Why?

#### chris10156

• Feb 17th, 2010

Voltage is not what kills someone, it is the amps.  4-5 amps is usually all it takes for the heart to stop and to kill someone.  100,000 volts would really sting, but it has an amperage so little that it does not harm anything.

• #### Engine Power

What does unit PS for the engine power means?

#### theleo

• Sep 4th, 2009

PS stands for Pferdestärken, a German measure for the power output of a car, equivalent to 1·01387 bhp.

• #### Air Scooper

What are the uses of air scooper?

#### senthil222

• Nov 25th, 2009

Its main function is to allow a direct flow of air to the engine, hence the need for it to be upraised so as to effectively channel air to the engine compartment. It may be closed, and thus purely decorative, or serve to enhance performance in several possible ways.

• #### Setting Down Operation

What is meant by setting down?

#### vrsaikumar

• Mar 25th, 2012

Setting down Operation is One of The Forging Operations, Others Being Drawing, upsetting, Fullering,bending punching,etc. when We Hammer down To Get Desired Shape,we can see the Hammer Spots which are...

• #### Frictional Force

What is the difference between tractive force and frictional force? Which one drives the vehicle? What are the directions of the forces with respect to the wheel?

#### bhargavmech

• Aug 29th, 2009

Yes you are right. But as you know that traction force is applied by the car wheels (tyres) against the ground. As the wheel is moving forward, the traction force is in the forward direction an...

#### NSK7777

• Aug 25th, 2009

Thanks for your reply, but I have a small doubt.Now consider a drive wheel rotating in a dry surface and other one on a icy surface.Slip do not occur in the first one because traction force is les...

• #### Bending Moment

What is the shape of bending moment diagram if a lone moment act at the mid point of the simply supported beam?

#### d_tyro_22

• Jan 27th, 2010

Expression for bending moment in terms of distance 'x' measured from left end:= -(Mx/L)          ; 0<=x<L/2=-(Mx/L) + M     ; L/2...

#### S.KALAIYARASAN

• Sep 19th, 2009

Triangle

• #### Convert Square Block to Circular Shaft

Which operation converts the square block into circular shaft?

#### Awais

• Jan 11th, 2013

Lathe machine can effectively do so. By turning and cutting operation through employing the workpiece in the jig of the machine

#### shashank khandelwal

• Dec 16th, 2012

Forging & Casting (after melting) etc.

• #### Lathe

How a lathe can be specified?

#### Gambit

• Sep 11th, 2009

Lathe can be specified in no. of ways:* Swing over bed (max. dia. of workpiece over the bed)* Swing over carriage* Distance between the headstock and tailstock* Bed height and Bed width* Shipping weight of lathe* Max. spindle speed etc.

#### vivekzgoal

• Sep 2nd, 2009

Lathe can specified in terms of its power in max speed of chuck.

• #### Energy Required to Break a Material

What is the energy required to break the material is called as?

#### Bhargav

• Jan 29th, 2016

A material withstands upto its shear stress. Beyond that, impact energy breaks the material.

#### S.Biswas

• Dec 27th, 2015

Energy required to break a material is specified as the modulus of toughness of that material.

• #### Refrigerator Tubes

In domestic refrigerator, What are the tubes at the back of the refrigerator called as?

#### Ian

• Mar 30th, 2018

What is the main water inlet tube called?

#### sudeeb

• Sep 17th, 2011

It is condenser coil assembly. The Pressurized, hot refrigerant from screw compressor will pass through this coil, heat transferred between the tube coil and the surrounding, as a result the refrigera...

• #### Archimedes' Principle

According to Archimedes principle, mass of an object in water would be less than mass of an object in air.So imagine an object of 5 kg and weight of a vessel containing water as 100 kg. The total weight is 105 kg. Now place a weighing machine under the water vessel and immerse the object into the water. Now can I except the weighing machine shows the weight less than 105 kg?

#### sudeeb

• Dec 20th, 2010

Acc to A.P -- Weight of the water displaced is equal to the weight of the body. So the weighing scale indicate the same weight 105 kg.  but when we lift the body we will feel low weight due to the upward bouncy force. and body float/sink depend upon the bouncy force and metacentre.

#### prashanthsekar

• Feb 19th, 2010

Firstly the question Cannot be directly related to Archimedes Principle, As the principle states that when an Body is immersed in water, The amount of water displaced by the body is equal to the weigh...

• #### Quality Governed Diesel

Why diesel is called as quality governed?

#### ravi

• Mar 29th, 2015

petrol - air fuel pre mixed and sent to engine. quality cannot be changed (rich or lean mix). By operating the throttle / accelerator the quantity of fuel is varied ( other than starting idling etc)....

#### sateesh

• Mar 18th, 2015

Basically petrol engines are quantity governing b coz , in this case fuel is mixed in the carburetor , so to change the speed we need to control the quantity of mixture that is going in the cylinder....

• #### Railway Engine Motor

What motor do they use in railway engines for traction?

#### hemalshah94

• Aug 27th, 2010

In Local memu train, series motor is used bec it  requires high torque initially e.g. Anand Memu, Vadodara memuIn Express train, I.M motor or Shunt motor is used bec. it requires high torque as well as constant speed e.g Ashram Express

#### bhargavmech

• Jul 28th, 2009

Traction motors used to drive trains are series motors that provide the required torque and horsepower to get massive amounts of weight moving

• #### Water Freezing Point

When salt is added to water, what happens to its freezing point?

#### vbijendra

• Sep 5th, 2009

For pure substances, there is no change in their freezing point, due to addition of impurities, freezing point decreases.

#### deepakjsd

• Jul 28th, 2009

Freezing point decreases.

• #### Disc Brake

Why do most of the vehicle have disc brake only in the front axle?

#### NSK7777

• Jul 26th, 2009

While applying brake, the momentum of the vehicle will be transferred to front portion so it is necessary to have more braking force on front axle, that is why disc brake is used in front axle.

#### Gambit

• Jul 19th, 2009

Most of the vehicles are front wheel drives which uses disc brake in the front axles. This is because the inertia of the vehicle towards the front is more. So, to control the speed it is necessary to ...

• #### Thermal Efficiency

Why the thermal efficiency of the engine decreases at part load?

#### deemech

• Jul 11th, 2010

Due to the practical irreversibilty and some losses

#### kanthasami

• Jul 26th, 2009

There are always some mechanical losses in the engine while running. These losses are more or less same at all the speeds. When the speed decreases, the output will obviously decreases. But, the losses remain same. So, the overall efficiency also decrease.

• #### Engine Test

How to find the max load of the engine?

#### Gambit

• Jul 17th, 2009

By using dynamometers.