Answer:
Option (b) is correct.
Explanation:
Elastic collision is defined as a collision where the kinetic energy of the system remains same. Both linear momentum and kinetic energy are conserved in case of an elastic collision.
Inelastic collision is defined as a collision where kinetic energy of the system is not conserved whereas the linear momentum is conserved. This loss of kinetic energy may due to the conversion to thermal energy or sound energy or may be due to the deformation of the materials colliding with each other.
As given in the problem, before the collision, total momentum of the system is 
and the kinetic energy is 
. After the collision, the total momentum of the system is , but the kinetic energy is reduced to 
. So some amount of kinetic energy is lost during the collision.
Therefor the situation describes an inelastic collision (and it could NOT be elastic).
Answer:
The wave speed is calculated below:
Explanation:
Given,
number of waves passed per minute = 8
time period = 1 minute = 60 s
distance between successive wave crests = 20 m
waves passing interval per second = 
Now,
wave speed = 20 m ×
= 
m/s
= 2.67 m/s
Hence the wave speed is 2.67 m/s.
An example of conductors of heat would be iron pans. a example of electric insulators would be copper, gold and silver. to contrast conductors and insulators, insulators let electricity pass through them while conductors restricts electricity. both conductors and insulators can work with lithium and sodium.
Crystalline crystals have sharp, well-defined melting points. Amorphous Solids don't have melting points.
Answer:
54.6°
Explanation:
From law of reflection i=r.
So, construct the reflected ray at 55.7°degrees from the normal and let it fall on the other mirror.
Now draw the second normal at the point of incidence and again measure the angle of incidence, and draw the angle of reflection.
If you consider triangle AOB, one angle is ∠AOB=90°
and ∠OAB is 54.6°
From angle sum property third angle ie ∠ABO=180°-90°-54.6°=35.4°
So, the second incident angle will be 54.6°
Hence, the second reflected angle will be 54.6 degrees.
