Answer:
1.63 s
Explanation:
The skier lands on the sloped section when the direction of its velocity is exactly identical to that of the slope, so at 
below the horizontal.
This occurs when the magnitude of the vertical velocity is equal to the horizontal velocity (in fact, 
, and since 
and so 
.
We already know the horizontal velocity of the skier:
And this is constant during the entire motion.
The vertical velocity instead is given by
where
is the initial vertical velocity (zero since the skier flies off horizontally)
g = 9.8 m/s^2
t is the time
Here we have chosen the downward direction as positive direction.
Substituting 
, we find the time:
The first one,second one and the forth one are correct
Answer:
F = 0.1575 N
Explanation:
When the third sphere touches the first sphere, the charge is distributed between both spheres, then now the first sphere has only half of his original charge.
In this moment then
Sphere one has a charge = Q/2
Sphere three has a charge = Q/2
Now when the third sphere touches the second sphere again the charge is distributed in a manner that both sphere has the same charge.
How the total charge is Q = Q/2 + Q = 3/2Q, when the spheres are separated each one has 3/4Q
Sphere two has a charge = 3/4Q
Sphere three has a charge = 3/4Q
The electrostatic force that acts on sphere 2 due to sphere 1 is:
F = 
F= 
how 
= 0.42
Then
F = 
F = 0.1575 N
I'm pretty sure it's D. negative acceleration
