When the life preserver is dropped from the helicopter, the only force acting on the object is the gravitational force. This modifies the equations of motion. Thus, the working equation is written below:
h = vt + 0.5gt²
where
v is the initial velocity
g is the acceleration due to gravity equal to 9.81 m/s²
h is the height of the fall
h = (1.46 m/s)(1.8 s) + 0.5(9.81 m/s²)(1.8 s)
h = 11.457 m
Correct answer choice is :
B) They are also called longitudinal waves.
Explanation:
S-waves, secondary waves, or shear waves are a kind of flexible wave also are one of the two principal kinds of elastic body waves, so called because they travel through the body of an object, unlike surface waves. It pushes and pulls the rock it travels through just like sound waves push and pull the air. The second kind of body wave is the S wave or secondary wave, which is the next wave you feel in an earthquake. An S wave is delayed than a P wave and can only move through solid rock, not through any fluid medium.
Explanation:
Let 
is the two forces acting on the raft. If they pull in the same direction, the net force is given by :
...............(1)
If they pull in opposite direction, net force is given by :
...............(2)
It is required to find the magnitude of both forces. On solving equation (1) and (2) we get :
So, the forces are 207.5 N and 92.5 N. Hence, this is the required solution.
