<span>The precautions which should
be taken on board a vessel during a lightning storm are:</span>
<span>(i) </span>All
electrical equipments should be unplugged.
<span>(ii) </span>Keep
yourself away from all metal parts such as engines, metal tanks, stoves etc.
<span>(iii) </span><span>Stay inside the boat. </span>
Answer:
B. the light will reach the front of the rocket at the same instant that it reaches the back of the rocket.
Explanation:
To an observer at rest in the rocket who can't see either sides of the rocket, the speed of the light is constant which means the distance to the front or the back is same and would appear to reach the rocket at the same time.
Although from the point of view of the person on the earth, the front of the rocket is travelling in opposite direction of the light while the back of the rocket is moving closer to the light. This means that the distance travelled by the light going forward will be longer going backwards. And since the speed of light is constant in both directions, the light will reach the back of the rocket before it reaches the front for the observer on the earth.
Answer:
Speed of cart's might be less than the high speed after 5 seconds.
Explanation:
Given that,
A fan cart with the fan set to high rolled across the floor.
Let the speed of fan cart with set to high is 
per second.
The fan supplies a force to the cart. If a lower fan speed were used, less force would be applied. This would cause a slower change in the cart's speed. So, the cart would be rolling more slowly than per second after 5 seconds. The speed of cart's might be less than per second.
Force is needed
A. for a moving object to keep moving at the same speed and direction
B. for a moving object to change its speed
C. for a motionless object to remain still
D. to prevent a moving object from turning
Hence,
Speed of cart's might be less than the high speed after 5 seconds.
Answer:
a) R = ρ₀ L /π(r_b² - R_a²)
, b) ρ₀ = V / I π (r_b² - R_a²) / L
Explanation:
a) The resistance of a material is given by
R = ρ l / A
where ρ is the resistivity, l is the length and A is the area
the length is l = L and the resistivity is ρ = ρ₀
the area is the area of the cylindrical shell
A = π r_b² - π r_a²
A = π (r_b² - r_a²)
we substitute
R = ρ₀ L /π(r_b² - R_a²)
b) The potential difference is related to current and resistance by ohm's law
V = i R
we subsist the expression of resistance
V = I ρ₀ L /π (r_b² - R_a²)
ρ₀ = V / I π (r_b² - R_a²) / L
