Answer:
Explanation:
Given
Charge discharged
time taken
Current is given as rate of change of discharge i.e.
Therefore, the average current is
If you can swim in still water at 0.5m/s, the shortest time it would take you to swim from bank to bank across a 20m wide river,
if the water flows downstream at a rate of 1.5m/s, is most nearly:
2 answers:
Answer:42.55 seconds
Explanation:
Check attached file for the diagram.
Vr= velocity of the river, if the water flows downstream, which is equal to 1.5m/s(from the question), Vb= my velocity at angle alpha which is perpendicular to the x-axis, and c= distance to swim from river bank to the other river bank.
Therefore, the shortest time to be taken to swim or cross the river,t=river with width of C÷ vertical component Vj.
Note that (vector) Vj= (vector)Vr+(vector)Vb.
Also, alpha must be maximum and for that to happen it must have a value of one(1).
Hence, time taken to cross the river,t= C/Vb× sin (alpha).
t= 20m÷ 0.5 ×sin 90.
t= 20÷ 0.47.
t= 42.55 seconds.
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Answer:
Explanation:
This is a recoil problem, which is just another application of the Law of Momentum Conservation. The equation for us is:
which, in words, is
The momentum of the astronaut plus the momentum of the piece of equipment before the equipment is thrown has to be equal to the momentum of all that same stuff after the equipment is thrown. Filling in:
Obviously, on the left side of the equation, nothing is moving so the whole left side equals 0. Doing the math on the right and paying specific attention to the sig fig's here (notice, I added a 0 after the 4 in the velocity value so our sig fig's are 2 instead of just 1. 1 is useless in most applications).
0 = 90.0v - 2.0 and
2.0 = 90.0v so
v = .022 m/s This is the rate at which he is moving TOWARDS the ship (negative was moving away from the ship, as indicated by the - in the problem). Now we can use the d = rt equation to find out how long this process will take him if he wants to reach his ship before he dies.
12 = .022t and
t = 550 seconds, which is the same thing as 9.2 minutes
Answer:
it takes the car 4.362 seconds to cover the distance of 88.4 m.
Explanation:
The distance the car covers is given by the function
,
where , and
, putting these in we get:
Now, when the car has moved to 88.4m, , or
which is a quadratic equation with solutions
We take the first solution , <em>since at that time the car is still moving right and decelerating</em>. The second solution
describes the situation where the car has stopped decelerating and is now moving leftwards because the decelerating is leftwards, <em>which is utterly wrong because we know that cars do not start moving backwards after the brakes have stopped them! </em>
Thus, it takes the car 4.362 seconds to cover the distance of 88.4 m.