Answer:
F = 2.49 x 10⁻⁹ N
Explanation:
The electrostatic force between two charged bodies is given by Colomb's Law:

where,
F = Electrostatic Force = ?
k = colomb's constant = 9 x 10⁹ N.m²/C²
q₁ = charge on proton = 1.6 x 10⁻¹⁹ C
q₂ = second charge = 1.4 C
r = distace between charges = 0.9 m
Therefore,

<u>F = 2.49 x 10⁻⁹ N</u>
Answer:
Answers A and D are the correct solution.
Explanation:
Both pots have the same mass and the same velocity vector.
the only difference between A and D is the selection of the reference frame positive direction.

Actually Welcome to the concept of Efficiency.
Here we can see that, the Input work is given as 2.2 x 10^7 J and the efficiency is given as 22%
The efficiency is => 22% => 22/100.
so we get as,
E = W(output) /W(input)
hence, W(output) = E x W(input)
so we get as,
W(output) = (22/100) x 2.2 x 10^7
=> W(output) = 0.22 x 2.2 x 10^7 => 0.484 x 10^7
hence, W(output) = 4.84 x 10^6 J
The useful work done on the mass is 4.84 x 10^6 J
Force applied by the machine to over come resistance
The vertical component is = vsinx m/s
If you know the angle, substitute the value of x.
If you know the velocity at which it is moving, substitute it for v
Hope it helps :)