Answer:
Explanation:
As a skydiver falls, he accelerates downwards, gaining speed with each second. The increase in speed is accompanied by an increase in air resistance. This force of air resistance counters the force of gravity.
<h2>
Speed of motorboat is 36 km/hr and speed of current is 4 km/hr.</h2>
Explanation:
Let speed of motor boat be m and speed of current be c.
A motorboat traveling with a current can go 160 km in 4 hours.
Distance = 160 km
Time = 4 hours
Speed = m + c
We have
Distance = Speed x Time
160 = (m+c) x 4
m + c = 40 --------------------- eqn 1
Against the current it takes 5 hours to go the same distance.
Distance = 160 km
Time = 5 hours
Speed = m - c
We have
Distance = Speed x Time
160 = (m-c) x 5
m - c = 32 --------------------- eqn 2
eqn 1 + eqn 2
2m = 40 + 32
m = 36 km/hr
Substituting in eqn 1
36 + c = 40
c = 4 km/hr
Speed of motorboat is 36 km/hr and speed of current is 4 km/hr.
Option (b) is correct.The index of refraction for the glass is 1.52
Explanation:
velocity of light in vacuum= C= 2.99 x 10⁸m/s
Velocity of light in glass = V= 1.97 x 10⁸m/s
The refractive index is given by n=
n= 2.99 x 10⁸/1.97 x 10⁸m/s
n= 1.52
Thus the refractive index of glass is 1.52
Index fossils (also known as guide
fossils, indicator fossils or zone
fossils) are fossils used to define
and identify geologic periods (or
faunal stages).
