Answer:
First let's find the work.
Work = Force*Displacement
= 20*5
= 100 Joules
Power = Work/Time
= 100/4
= 25 Watts
UMUC. this is for the blank answer.
Answer:
The vision becomes blurred due to the refractive defects of the eye. There are mainly three common refractive defects of vision. These are (i) myopia or near-sightedness, (ii) Hypermetropia or far – sightedness, and (iii) Presbyopia. These defects can be corrected by the use of suitable spherical lenses.
In physics, there are already derived equation that are based on Newton's Law of Motions. The rectilinear motions at constant acceleration have the following equations:
x = v₁t + 1/2 at²
a = (v₂-v₁)/t
where
x is the distance travelled
v₁ is the initial velocity
v₂ is the final velocity
a is the acceleration
t is the time
Now, we solve first the second equation. Since it mentions that the car comes eventually to a stop, v₂ = 0. Then,
-5 = (0-v₁)/t
-5t = -v₁
v₁ = 5t
We use this new equation to substitute to the first one:
x = v₁t + 1/2 at²
15 = 5t(t) + 1/2(-5)t²
15 = 5t² - 5/2 t²
15 = 5/2 t²
5t² = 30
t² = 30/5 = 6
t = √6 = 2.45
Therefore, the time it took to travel 15 m at a deceleration of -5 m/s² is 2.45 seconds.
