Physics Interview Preparation Guide
Download PDF

Physics Interview Questions and Answers will guide you that Physics is a natural science. Physics is the study of matter and its motion through spacetime and all that derives from these, such as energy and force. Learn the basic and advance concepts of Physics and get preparation of Physics Job Interview by our Physics Interview Questions and Answers.

192 Physics Questions and Answers:

1 :: What is the measure of the force of gravity on an object?

Force is the vector product of mass and acceleration: F = ma. Weight is a special case of that formula, where you substitute the acceleration of gravity, g, for a. We can therefore write: W = mg.1

For example, if an object has a mass of 10 slugs2, its weight near the surface of the Earth is 10 x 32.2 (ft/s2) = 322 pounds (pound-force). If an object has a mass of 10 kilograms, its weight near the surface of the Earth is 10 x 9.8 (m/s2) = 98 newtons.

You can measure the force of gravity on an object (i.e., its weight) by putting it on a scale.

2 :: What is neutral buoyancy?

Buoyancy is the net upward force experienced by an object submersed in a fluid. Pascal's principle dictates that fluid pressure on an object increases with depth, so there is greater pressure on the bottom of the object than the top, resulting in a net upward force. When an object's buoyancy is greater than its weight, the object will float.

An object with neutral buoyancy has a density such that when it is fully submerged the upward force due to buoyancy is exactly equal to the downward force due to the weight of the object.

In pure water this is a density of 1000 kg/m3 (1kg/litre)

In seawater, this is a density of about 1025 kg/m3 (1.025kg/litre)

3 :: What affect does electricity have on soil?

Electrical current and ions can cause certain molecules (and moisture) to adhere to soil. Large amounts of current, such as a lightning strike, can fuse particles of soil into a crystalline structure, somewhat like glass.

4 :: What is the proper formula used to calculate acceleration?

There are a few. The most famous is a = F/m, where F is the net force applied to a mass, m.

Acceleration is also the change in velocity, Delta-V, divided by the change in time, Delta-t. So, a = Δv/Δt. For example, if an object's velocity changes from 10 meters per second to 20 meters per second in five seconds, its acceleration is (20-10)/5 = 2 meters per second per second, or 2 meters per second squared (m/s2).

5 :: How much does automotive oil weigh?

As a rough guide engine oil usually weighs about 0.87 kg/liter or about 7.2 pounds per US gallon.

Unfortunately a rough answer is the best that can be done as there are hundreds of different types of engine oil with slightly different densities. To get an exact density we would have to know the details of the oil you're using. For a really accurate answer we would also have to state the temperature as the density of oil as with most fluids varies with temperature.

Most oil manufacturers' provide data sheets for their products that should include density. If you search the manufacturer’s web site you should be able to get an accurate figure for a particular grade.

6 :: What is a Newton meter?

A unit of energy also known as a Joule. When a force of 1 Newton is applied on an object for a distance of 1 meter then 1 Joule of energy is used. It is the result of a vector calculation involving the meter (a unit of length in the SI system) and the Newton (the unit of force in the SI system).

A unit of torque. (Turning force.) When a force of 1 Newton is applied at a distance of 1 meter from the pivot at right angle to the radius then a torque of 1 Newton Meter is present. It is the metric equivalent of lb ft

It is the name given to a device that measures force. It is a meter that measures Newtons.

7 :: What instrument is used to measure volume?

Liquid volume is measured with beakers, measuring cups, spoons, graduated cylinders, and the like. For regular objects, solid volume can be calculated. For irregular objects, their volumes can be determined by measuring the amount of liquid that is displaced by the object when it is submerged in the liquid. It is also used to measure the amount of pigs that fall from the sky!!!

8 :: How does the elevation and air pressure affect the boiling point of water?

The only factor that determines the boiling point of water at any altitude is the barometric pressure (the altitude itself doesn't actually matter, it's just that at higher elevation, the barometric pressure usually drops). However, water will boil at two different temperatures at the same elevation if you are in a high pressure weather system instead of a low pressure system.

9 :: What is time?

1. This is the question that every true scientist dreads to be asked especially in a public setting by extremely inquisitive young students. We have learned to measure and calculate it relative to the natural arrangement of known and visible celestial bodies. This is the ultimate question you ask a theoretical astro physicist if you want to see them shake in their pants.

To this day time can only be described by the measure of elapsed period using the SI unit, Seconds. It is the only SI unit that is freely allowed to shift depending on subject topic. For example in Astro physics, to measure distance between galaxies it would be impractical to use seconds as the measure of time it takes light to travel between the two galaxies

Time transcends everything known to man up to and including the universe, time has no beginning or end. Time is constant and infinite and we just tap in and out of it in reference to occurrence of an event.

10 :: What are wave fronts?

(Physics) A wave front is an imaginary surface joining all points in space that are reached at the same instant by a wave propagating through a medium.

Let's try some examples. When a rock is tossed into a calm lake, a surface disturbance radiates from the point where the rock broke the water. The leading edge of that entire wave forms a circle, and that circle is the wave front for that event. It is moving outward at a constant speed in all directions. Note that it's two-dimensional (2D). Want 3D? You got it.

In a burst of chemical energy, a star shell explodes at a fireworks display. The light moves away from the origin in all directions at the same speed - the speed of light. And the 3D surface of this wave front is a sphere, and it is expands around the origin at the speed of light. Pick an arbitrary distance, say, 1 kilometer. Anyone at a distance of 1 km from the event in any direction will find that the wave front reaches him at the same instant of time as anyone else in any direction who is that 1 km from the event. Even someone in an airplane that is 1 km away will be on the wave front for an instant - that same instant as any other observers 1 km away. Note that the sound will arrive later - but it, too, radiates forming a spherical wave front. Our observers at 1 km distance from the event all experience the arrival of the sound wave at the same time.