Answer:
Mechanical
Explanation:
Electromagnetic waves are waves that have no medium to travel whereas mechanical waves need a medium for its transmission.
Answer:
9 times
Explanation:
Kinetic energy is:
KE = ½ mv²
When we triple the velocity, the kinetic energy increases by a factor of 9.
9KE = ½ m(3v)²
While plane is moving under tailwind condition it took time "t"
so here we will have

here net speed of the plane will be given as


similarly when it moves under the condition of headwind its net speed is given as

now time taken to cover the distance is 2 hours more

now solving two equations

solving above for v_w we got

Answer:
Specific gravity is 0.56
Explanation:
We know that
mass of water displaced by the wood is, m1( apparent mass when wood in air and lead is submerged in water) - m2(the apparent mass when wood and lead both are submerged in water)
= 0.0765 - 0.0452 = 0.0313 Kg
So the specific gravity of the wood is, = mass of wood / mass of water displaced by the wood
= 0.0175/0.0313
=0.56