Answer:
length f′0 when the eye is presbyopic and by a screen (the retina) at the distance d from the
Explanation:
Your potential energy at the top of the hill was (mass) x (gravity) x (height) .
Your kinetic energy at the bottom of the hill is (1/2) x (mass) x (speed)² .
If there was no loss of energy on the way down, then your kinetic energy
at the bottom will be equal to your potential energy at the top.
(1/2) x (mass) x (speed)² = (mass) x (gravity) x (height)
Divide each side by 'mass' :
(1/2) x (speed)² = (gravity) x (height) . . . The answer we get
will be the same for every skater, fat or skinny, heavy or light.
The skater's mass doesn't appear in the equation any more.
Multiply each side by 2 :
(speed)² = 2 x (gravity) x (height)
Take the square root of each side:
<u>Speed at the bottom = square root of(2 x gravity x height of the hill)</u>
We could go one step further, since we know the acceleration of gravity on Earth:
Speed at the bottom = 4.43 x square root of (height of the hill)
This is interesting, because it says that a hill twice as high won't give you
twice the speed at the bottom. The final speed is only proportional to the
<em>square root </em>of the height, so in order to double your speed, you need to
find a hill that's <em>4 times</em> as high.
Answer: Option A: 22.5 m
Explanation:
A stone is dropped from a tower. The initial velocity of the stone, u = 0.
Height of the tower, y = 100 m
Let the depth of the well be d.
Time taken of the drop of the stone, t = 5 s
The stone falls under acceleration due to gravity g = 9.81 m/s²
We will use second equation of motion:
s = u t + 0.5 g t²
⇒100 m + d = 0 + 0.5 × 9.81 m/s²× (5.00 s)²
⇒d = (122.6 - 100) m = 22.6 m ≅ 22.5 m
Thus, the correct option is A. The depth of the well is 22.5 m.
Answer:
a) 0.162 V/m
b) 0.54 nT
c) 22 kW
Explanation:
Given
Distance of flight, d = 20 km
Intensity of signal, I = 35.1 μW/m²
Magnitude of the electric component is gotten using the formula
E(m) = √(2Iμc), where
E(m) = √(2 * 35*10^-6 * 4*3.142*10^-7 * 3*10^8)
E(m) = √(2 * 35*10^-6 * 1.257*10^-6 * 3*10^8)
E(m) = √0.0264
E(m) = 0.162 V/m
Magnitude of magnetic component can be gotten by using the relation
B(m) = E(m) / c
B(m) = 0.162 / 3*10^8
B(m) = 5.4*10^-10
B(m) = 0.54 nT
Transmission power, P = IA
where A = 1/2 * 4πr²
P = 2Iπr²
P = 2 * 35*10^-6 * 3.142 * (10000)²
P = 2 * 35*10^-6 * 3.142 * 1*10^8
P = 21994 W
Thus, the transmission power is 22 kW
A head on collision would be worse and it would actually be four times as worse since the speed is doubled and energy is a squared value so by far a head on collision with another car
