Answer:C
Explanation:
When a constant horizontal force is applied to the box, box started moving in the horizontal direction such that it moves with constant velocity 
Constant velocity implies that net force on the box is zero
i.e. there must be an opposing force which is equal to the applied force and friction force can serve that purpose.
So option c is the correct choice.
Answer:
m = 4.4 × 10³ kg
Explanation:
Given that:
The total yearly energy is 4.0 × 10²⁰ J
The amount of mass that provides this energy can be determined by using the formula:
E = mc²
where;
c = speed of light in free space = (3 × 10⁸)
4.0 × 10²⁰ = m × (3 × 10⁸)²

m = 4.4 × 10³ kg
D. Nucleus because it is not a part of the group.
This would be false. hope this helps. good luck :)
Answer:
Some lenses are used to focus light to a pre-defined point based on the amount of curvature of their surfaces.
In a piano design convex, some surfaces are flat while others has positive lenses (biconvex)
Explanation:
Solution
These lenses are applied to pay attention to light in a point pre-defined based on the amount of curvature of their surfaces.
For that of a plano-convex design, one surface has a positive curve and for biconvex lenses, both surfaces are positively curved while the other remains flat.
when used practically, plano-convex lenses are most commonly used where the object being imaged is far apart from lens.