Answer:
t = 3.414 s
s = 23.3 m
Explanation:
Let t be the total time of motion
Let s be the total distance of motion
s - s/2 = ½at² - ½a(t - 1²) = ½a(t² - (t - 1)²)
s/2 = ½a(t² - (t² - 2t + 1)) = ½a(t² - t² + 2t - 1)
s = a(2t - 1)
s = 4(2t - 1)
s = 8t - 4
8t - 4 = ½4t²
8t - 4 = 2t²
0 = 2t² - 8t + 4
0 = t² - 4t + 2
t = (4 ±√(4² - 4(1)(2))) / 2 = (4 ± √8)/2 = 2 ± √2
t = 3.414 s
or
t = 0.5857... s which we ignore because it does not have a full last second.
s = ½(4)3.414² = 23.3137... 23.3 m
Answer:
D
Explanation:
D) The overall work done by gravity is zero
This statement is correct .
If m be the mass of each of the children and h be the height of tower
work done by gravity on the boys in going up = - mgh
it is so because force applied by gravity = mg downwards and displacement
is upwards
work done will be negative = - mgh
Work done by gravity on boys when they come down = + mgh because both force and displacement are downwards .
Hence total work done = - mgh + mgh = 0.
The children will have same kinetic energy as the inclined surface is friction-less so no energy will be dissipated hence addition of energy to boys in both the cases will be same.
Answer:
It is True
Explanation:.
A commander assigns a zone reconnaissance mission when he seeks additional information on a zone before committing other forces in the zone. It is appropriate when the enemy situation is vague, existing knowledge of the terrain is limited, or combat operations have altered the terrain. A zone reconnaissance could include several route or area reconnaissance missions assigned to subordinate units.
2.6 sec (look it up) for more accurate
