Answer is D.
Speed:
Use relative speed to simplify the situation. Since the trains are moving in opposite directions, you can add the speeds and pretend the first train is stationary (moving at 0m/s) and the second train is moving at 50m/s.
Distance:
The front of the second train needs to travel 120m to get from the front to the back of the first train. When the front of the second train is at the back of the first train, the back of the second train is still 10m in front of the first train. The back therefore has to travel 130m to clear the first train. The total distance over which the trains are overlapping in this scenario is therefore 120 + 130 = 250m.
You have speed and you have distance so now just calculate time:
v = d / t
50 = 250 / t
t = 5s
They eat rice, chicken, beef, cereal they eat what we eat in a daily basis I guess
<u>Answer:</u> The remaining sample of X is 6.9 grams.
<u>Explanation:</u>
All the radioactive reactions follow first order kinetics.
The equation used to calculate rate constant from given half life for first order kinetics:
We are given:
Putting values in above equation, we get:
The equation used to calculate time period follows:
where,
= initial mass of sample X = 78 g
N = remaining mass of sample X = ? g
t = time = 16.5 min
k = rate constant = 
Putting values in above equation, we get:
Hence, the remaining amount of sample X is 6.9 g
Answer:
0.055 N
Explanation:
From coulomb's law,
F α 1/r²
F = k/r²
F₁r₁² = F₂r₂²......................... Equation 1
Where F₁ = Initial force, r₁ = initial distance, F₂ = Final force, r₂ = Final distance.
making F₂ the subject of the equation
F₂ = F₁r₁²/r₂²..................... Equation 2
Given: F₁ = 5.50 N.
Let: r₁ = x m, then r₂= 10x m
Substitute into equation 2
F₂ = 5.5(x²)/(10x)²
F₂ = 5.5x²/100x²
F₂ = 5.5/100
F₂ = 0.055 N.
Hence the force becomes 0.055 N
