Physics - Study Mode

[#726] The point where total mass of a body is supposed to be concentrated is known as
Correct Answer

(B) Centre of mass

Explanation

Solution: The centre of mass of a body or a system of particles is defined as a single point at which the whole mass of the body or system is imagined to be concentrated and all the applied forces acts at that point. It is that point that moves when forces are applied on the body.

[#727] The angle in which a cricket ball should be hit to travel maximum horizontal distance is :
Correct Answer

(B) 45° with horizontal

Explanation

Solution: The angle in which a cricket ball should be hit to travel maximum horizontal distance is 45° with horizontal.

[#728] Water cannot be used to extinguish fire caused by electric current, because
Correct Answer

(A) It may cause electrocution

Explanation

Solution: Using water for putting out electric fires is risky, as the firemen can be electrocuted by the water jet. Water is a good conductor of electricity, and, the electric current flows through the water-jet directly into the hands of the person who is holding the waterhose, resulting in immediate electrocution.

[#729] Brightness of bulb depends on voltage or current?
Correct Answer

(C) Both A & B

Explanation

Solution: Brightness of bulb depends on both voltage and current. The brightness depends on power. Since we know that Power (P) = Voltage x Current = V I So whether you increase the current or the voltage the brightness will increase.

[#730] The resistance of a conductor is inversely proportional to its:
Correct Answer

(D) Area of cross section

Explanation

Solution: The resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area. Resistance also depends on the material of the conductor.