Answer
4.8 N
If the box is moving with a constant velocity, then we can say that the system is in equilibrium. This is because if the external force (F->) was greater than other forces the box would be accelerating. This tells us that this force (F->) is just enough to overcome friction and so it must be equal to 4.8 N.
The normal force has no effect to the horizontal velocities or forces. It is equal to -Weight. That is -74 N. The negative sign shows that the force is in opposite direction.
Johann Strauss II
hope this helps
Answer:
q = 4.87 X 10^ -14 C
Explanation:
As d=0.350 mm
The ink drop will be accelerated by the electric field between the plates:
a = F/m
d = a(D0 / v)^2 / 2 ...... 1
a = qE/m ............... 2
Substituting 2 into 1:
d = (qE/m)(D0 / v)^2 / 2
q = 2mdv^2 / [E(D0)^2]
q = 2(1.00e-11 kg)(3.50e-4 m)(15.0 m/s)^2 / [(7.70e4 N/C)(2.05e-2 m)^2]
q = 4.87e-14 C
1 year = (365 / 121) = 3.02 half-lifes. Let's call it 3 .
The amount of radioactive isotope remaining after 3 half-lifes is
(1/2) x (1/2) x (1/2) = 1/8
A year after the medical lab received the 24 kg of W-181,
there will still be 24 kg of stuff in the container.
But only 3 kg of it will still be W-181. The other 21 kg will be
whatever substances W-181 becomes when it decays.
Sadly, even the 3 kg of good stuff won't be usable anymore ...
it'll be thoroughly mixed with the 21 kg of junk. It would be harder
and more expensive to try and separate them than to buy a new
can of pure W-181, and USE it before 7/8 of it has deteriorated.
