Answer:
a. 13.7 s b. 6913.5 m
Explanation:
a. How much time before being directly overhead should the box be dropped?
Since the box falls under gravity we use the equation
y = ut - 1/2gt² where y = height of plane above ocean = 919 m, u = initial vertical velocity of airplane = 0 m/s, g = acceleration due to gravity = -9.8 m/s² and t = time it takes the airplane to be directly overhead.
So,
y = ut - 1/2gt²
y = 0 × t - 1/2gt²
y = 0 - 1/2gt²
y = - 1/2gt²
t² = -2y/g
t = √(-2y/g)
So, t = √(-2 × 919 m/-9.8 m/s²)
t = √(-1838 m/-9.8 m/s²)
t = √(187.551 m²/s²)
t = 13.69 s
t ≅ 13.7 s
So, the box should be dropped 13.69 s before being directly overhead.
b. What is the horizontal distance between the plane and the victims when the box is dropped?
The horizontal distance x between plane and victims, x = speed of plane × time it takes for box to drop = 505 m/s × 13.69 s = 6913.45 m ≅ 6913.5 m
When using a simple machine, the benefit of using less force to lift an object is offset by the need to push for a larger distance so that energy can be conserved.
<u>Explanation:
</u>
A simple machine utilized for completing the works easily. So in order for easy and quick completion of works, these machines may increase the amount of force acting on the object by increasing the velocity or speed of the machine. As velocity term is present so the machines may also change the directions of force acting on the object of concern to do the work soon just like pulley.
Also other way of completing the work with less input force requirement is by increasing the distance or area of action for the force acting on it. As work done is a measure of acting force on a region multiplied with the displacement occurred with that force.
It can be known that force seems to be inversely proportional to distance or area of action. So if we need to use less force to lift an object, it is offset by the need to push for a larger distance in order to conserve the energy.
The answer to it is the letter A
167•F which is c
Tell me my wrong from right
