Answer:
0.23 s
Explanation:
First of all, let's find the time constant of the circuit:
where
is the resistance
is the capacitance
Substituting,
The charge on a charging capacitor is given by
(1)
where
is the full charge
we want to find the time t at which the capacitor reaches 90% of the full charge, so the time t at which
Substituting this into eq.(1) we find
Answer:
Explanation:
The ball will rise decreasing its speed until it reaches the highest point where its speed will be zero. From this point the tennis ball will begin to fall again, in the free fall the tennis ball will gain speed but now in the opposite direction. When it returns to the same point where it was launched, its speed will be the same as the one that was launched but with the opposite sign.
We can check this using the equation:
where
ang h is the height, but because the ball returns to the same point where it started, h =0
then
the initial and final velocity will be the same in number, but we know that the ball is going in the opposite direction, so the final velocity must have the opposite sign from the initial velocity
so if ,