Physics - Study Mode

[#651] In SONAR which kind of wave is used?
Correct Answer

(B) Ultrasonic

Explanation

Solution: In SONAR ultrasonic wave is used.

[#652] Sound waves cannot travel through
Correct Answer

(C) Vacuum

Explanation

Solution: Sound waves cannot travel through vacuum.

[#653] A body of mass 2 kg is thrown upward with initial velocity of 20 m/s. After 2 seconds, its kinetic energy will be : (g = 10 m/s 2 )
Correct Answer

(A) 0 J

Explanation

Solution: We will use the following equation of motion to get the final velocity after 2 seconds. V = u - gt U = 20 m/s g = 10 t = 2 V = 20 - 2 × 10 V = 20 - 20 V = 0 K.E = 1/2mv² m = 2 v = 0 K.E = 0.5 × 0 × 2 = 0

[#654] The energy stored in a watch spring is
Correct Answer

(B) Potential energy

Explanation

Solution: When a spring is compressed, it stores energy in form of elastic potential energy.

[#655] An object that has kinetic energy must be
Correct Answer

(D) Moving

Explanation

Solution: In physics, we know that the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Hence, An object that has kinetic energy must be in motion i.e, moving.