A parachute is a device used to slow down an object that is falling towards the ground. without a parachute the gravity is more than air resistance. But, as the parachute opens, the air resistance increases.
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I choose the option D.
The velocity is constant, so it’s acceleration is 0 m/s^2.
X = 2 + 15 x 1 + 0 = 17 m
Answer:
t = 6 s
Explanation:
This is a free fall exercise
y = y₀ + v₀ t - ½ g t²
If the balloon is released its initial velocity is zero, when it reaches the floor its height is also zero, we substitute
0 = y₀ + 0 - ½ g t2
t = √(2yo / g)
let's calculate
t = √ (2 176.4 / 9.8)
t = 6 s
the balloon must be released 6 s before the person reaches the building
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Answer:
Option C and D only
Explanation:
Option A is incorrect because refractive index of a material is the ratio of speed of light in vacuum to the speed of light in a any given medium
Option B is correct as the speed of light in vacuum is always greater than the speed of light in any given medium.
Option C is correct
Option D is incorrect
Option E is incorrect because the denser the medium the more is the refractive index. Water is denser than air, hence it should have more refractive index as compared to that of air.
Density reduces
Explanation:
The density of a fluid will reduce as a substance gains more thermal energy. Heat is a form of thermal energy usually noticed as temperature differences in a matter.
- When thermal energy is gained by a body, the temperature of the body rises.
- The particles of the medium gains more kinetic energy.
- This causes the substance to expand and it has more volume.
- When a substance expands, it occupies more space.
- The more the volume a body occupies, the lesser the density.
- Expansion does not change the mass of the fluid but the volume changes.
- This is why density decreases.
Learn more:
Density brainly.com/question/8441651
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