Answer:
55.6 nC
Explanation:
The electric field at the surface of a charged sphere has the same expression of the electric field produced by a single point charge located at the centre of the sphere and having the same charge of the sphere, so it is given by

where
is the Coulomb's constant
Q is the charge on the sphere
r is the radius of the sphere
In this problem we know
E = 890 N/C is the magnitude of the electric field on the sphere
r = 0.750 m is the radius of the sphere
So by re-arranging the equation we can find the net charge on the sphere:

Answer:
W of the person in moon ≈ 124.70 N
Explanation:
Weight: Weight of a body can be defined as the product of mass and the gravitational acceleration of the body. The S.I unit of weight is Newton (N). It can be expressed mathematically as
W = mg
Where W = weight of the body, m = mass of the body (kg) and a = acceleration of the body (m/s²)
Weight(W) = Mass (m) × Acceleration due to gravity (g)
∴ W = m × g.
If the person is on the moon,
Mass = 76.5 kg.
g (moon) = 16.6% of g ( earth)
But g(earth) = 9.80 m/s².
∴ g (moon) = 9.80 × (16.6/100)
g (moon) = 1.63 m/s², m = 76.5 Kg
∴ Weight of the person in moon = 76.5 × 1.63 =124.695 N
W of the person in moon ≈ 124.70 N
Answer:
Explanation:
Laminar Flow is a very important topic discussed in physics in the subject of fluid dynamics. Basically, it explains how fluid particles behave at lower velocities. In such cases and when the viscosity of the fluid is low, the fluid particles flow smoothly in perfectly perpendicular layers that do not collide or cross each other. Unlike turbulent flow, which is the opposite. An example of Laminar flow can be seen when you open up a water hose with little pressure, the water simply flows out of the hose and looks very clear and smooth.
Refer to the attached figure. Xp may not be between the particles but the reasoning is the same nonetheless.
At xp the electric field is the sum of both electric fields, remember that at a coordinate x for a particle placed at x' we have the electric field of a point charge (all of this on the x-axis of course):

Now At xp we have:


Which is a second order equation, using the quadratic formula to solve for xp would give us:

or

Plug the relevant values to get both answers.
Now, let's comment on which of those answers is the right answer. It happens that
BOTH are correct. This is simply explained by considring the following.
Let's place a possitive test charge on the system This charge feels a repulsive force due to q1 but an attractive force due to q2, if we place the charge somewhere to the left of q2 the attractive force of q2 will cancel the repulsive force of q1, this translates to a zero electric field at this x coordinate. The same could happen if we place the test charge at some point to the right of q1, hence we can have two possible locations in which the electric field is zero. The second image shows two possible locations for xp.