7
Q:

Skating on ice is possible because

 A) the surface of ice is smooth B) ice is cold C) the pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water D) the pressure on the ice due to skate raises its melting point

Answer:   C) the pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water

Explanation:

Here is a case of  lowering of melting point of ice with increase of pressure

Subject: Physics
Q:

Light from the sun reaches us in nearly

 A) 5 min B) 4.30 hrs C) 8 min D) 5.30 hrs

Answer & Explanation Answer: C) 8 min

Explanation:

The light from the sun takes about 8 minutes to reach the Earth after it has been emitted from the sun's surface.

The time it takes for light to reach planets in our Solar System varies from about 3 minutes for Mercury to about 5.3 hours for Pluto.

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0 70
Q:

Which component of an IED creates an electrical charge?

 A) activator B) fuse C) explosive D) power source

Answer & Explanation Answer: D) power source

Explanation:

The power source such as a Battery of an IED creates an electrical charge.

What are IED's ::

An Improvised Explosive Device (IED) is a bomb constructed and deployed in ways other than in conventional military action. It may be constructed of conventional military explosives, such as an artillery shell, attached to a detonating mechanism. IEDs are commonly used as roadside bombs.

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0 61
Q:

What is a Contact Force and explain with an example?

A Contact force is a force applied to a body by another body that is in contact with it. Contact force acts on a point of direct contact between the two objects. This force can either be continuous as a continuous force or can be momentary in the form of an impulse. Contact force is governed by Newton’s Laws.

Examples :: Contact force is responsible for most of the interactions we experience in the daily life.

1. Writing your name with a pen, pushing a car up a hill, lifting an object, etc...

2. Kicking a ball, hammering a nail, etc...

are some of the everyday examples where contact forces are at work.

In the first case, the force is continuously applied by the person on the car or pen or an object while in the second case the force is delivered in a short impulse.

Contact forces are often decomposed into orthogonal components

one perpendicular to the surface in contact called the normal force, and

one parallel to the surface in contact, called the friction force.

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23
Q:

The ability to do work is called Energy.

 A) TRUE B) FALSE

Explanation:

Yes, the ability to do work is called Energy is True.

Subject: Physics
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0 28
Q:

Sound waves cannot travel through

 A) Gas B) Liquid C) Vacuum D) Solid

Explanation:

Sound waves cannot travel through a Vacuum.

A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.

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0 24
Q:

Which of the following is the fastest communication channel?

 A) Microwave B) Optical fiber C) Radio wave D) All are operating at nearly the same propagation speed

Explanation:

A microwave is the fastest communication channel whereas Optical fiber is a way of transferring data not a way of communication.

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1 109
Q:

If a barometric reading is falling, this usually indicates what

 A) Increasing pressure B) Decreasing pressure C) No pressure D) None

Answer & Explanation Answer: B) Decreasing pressure

Explanation:

A barometer is a tool that measures air pressure

A rising barometer indicates increasing air pressure, a falling barometer indicates decreasing air pressure.

In space, there is a nearly complete vacuum, so the air pressure is zero.

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1 86
Q:

Metals are good conductors of electricity because

 A) The atoms are lightly packed B) They contain free electrons C) They have high melting point D) All the above

Answer & Explanation Answer: B) They contain free electrons

Explanation:

Metal particles are held together by strong metallic bonds, which is why they have high melting and boiling points. The free electrons in metals can move through the metal, allowing metals to conduct electricity.

Because the electrons in the atom's higher energy levels can separate from the atoms easily, they can be pulled out with very little energy. Because the molecular structure of the metal is such that 'free electrons' are free to move, thus being categorized as electrically conductive.

For example, copper is used for electrical wiring because it is a good conductor of electricity.