Answer:

Explanation:
Since the formula for kinetic energy of an object is:

Where m is the mass of the object and v is the speed. We can substitute m =
kg and v = 17900m/s:

Answer:
Explanation:
Velocity of sound in air at 20 degree = 343 m/s
Velocity of sound in water at 20 degree = 1470 m/s
Time taken in to and fro movement in air
=( 2 x 10) / 343 = 0.0583 s
Rest of the time is
.171 - .0583 = .1127 s
This time is taken to cover distance in water. If d be the depth of lake
2d / velocity = time taken
2 d / 1470 = .1127
d = 82.83 m
Answer:
54 km/h
Explanation:
given,
speed of the biker = 36 Km/h
time = 10 s
acceleration = 0.5 m/s²
speed at which it crosses the finish line = ?
v = 36 x 0.278 = 10 m/s
using equation of motion
v = u + a t
v = 10 + 0.5 x 10
v = 15 m/s
v = 15 x 3.6 = 54 km/hr
speed at which the biker crosses the finish line is equal to 54 km/h