Answer:
a) t = 4.14 s
b) Speed with which it hits the ground = 40.58 m/s
Explanation:
Using the equations of motion,
g = 9.8 m/s², y = H = 84 m,
Initial velocity, u = 0 m/s,
final velocity, v = ?
Total Time of fall, t = ?
a) y = ut + gt²/2
84 = 0 + 9.8t²/2
4.9t² = 84
t² = 84/4.9
t = 4.14 s
b) v = u + gt
v = 0 + (9.8 × 4.14)
v = 40.58 m/s
Answer: When a material is heated or cooled, two changes may happen to the particles within the material: Chemical bonds between the particles may form, break or stretch. There is a change in the chemical potential store of energy in the material. The material will heat up or cool down as the particles within it gain or lose speed.
Explanation:
This is EXACTLY the same scenario as the skydiver jumping
out of the airplane, except the whole thing is turned on its side.
==> The skydiver leaves the airplane.
The force of gravity on him (his weight) makes him accelerate down.
But the air resists his downward motion.
The faster he falls, the more UPWARD force the air exerts on him.
The more upward force the air exerts, the less he accelerates down.
When his falling speed is great enough, he stops accelerating, and
falls with a constant speed. He calls that speed his 'terminal velocity'.
==> The submarine turns on its engines, at maximum power.
The force of the engines makes the sub accelerate forward.
But the water resists its forward motion.
The faster it moves, the more BACKWARD force the water exerts on it.
The more backward force the water exerts, the less it accelerates forward.
When the forward speed is great enough, it stops accelerating, and moves
with a constant speed. I don't know if they use the same term in submarines,
but you might say that speed is the 'terminal velocity' in water.
Free fall means rapid fall or a downward motion due to gravity. Sentence example: When Joe was accidentally bumped by Sarah, he was sent towards a free fall down the escalator, leading to a serious injury on his arm and two legs.
