Answer:
1400 units of momentum.
Explanation:
Using the formula p=mv. We can get the momentum using 70*20 =1400 units of momentum
The expression of the electric flux is

Here,
Q = Total charge enclosed in the closed surface
= Permittivity due to free space
Rearranging to find the charge,

Replacing with our values we have finally



The charge enclosed by the box is 0.1684nC
The sign of the charge can be decided by using the direction of the flux. The charge enclosed by the cube can be calculated by using the electric flux and the permitivity of free space.
Answer:
A
Explanation:
The answer would be A because when feet push down on anything, the force will push down the skateboard
The refractive index for glycerine is

, while for air it is

.
When the light travels from a medium with greater refractive index to a medium with lower refractive index, there is a critical angle over which there is no refraction, but all the light is reflected. This critical angle is given by:

where n1 and n2 are the refractive indices of the two mediums. If we susbtitute the refractive index of glycerine and air in the formula, we find the critical angle for this case: