Answer:
The wall is 680 meter away from the person.
Explanation:
Given data
Speed of sound = 340 
Given that Persons said hello toward the opposite side she has an echo hello 4 seconds later means it takes 2 seconds for the sound to reach the wall & again 2 seconds to reach the persons ear.
Therefore the distance between the person & wall is
D = speed × Time
D = 340 × 2
D = 680 meter
Therefore the wall is 680 meter away from the person.
Answer:
energy of position
Explanation:
I think that is the answer
given that acceleration due to gravity is g = 10 m/s^2
speed of the rocket will reach to 0.9c

now by kinematics



Part b)
distance traveled by it in above time



so this is the distance covered by the object