Acrate of apples weighing 71.4 n sits at rest on a ramp that runs from the ground to the bed of a truck. the ramp is inclined at 20.0° to the ground. what is the interaction partner of normal force?
1. if the interaction partner is acting above the surface of the ramp, enter a positive value.
2. if the interaction partner is acting below the surface of the ramp, enter a negative value.

Fint = - 67.094 N

Explanation:

Given

W = 71.4 N

∅ = 20º

Fint = ?

The interaction partner of the Normal Force has equal magnitude and opposite direction to the Normal Force, and it is a contact force exerted by the crate on the ramp, because the interaction parteners are the same force acts on the two object.

Then:    Fint = - N = - Wy' = - W*Cos ∅  

⇒   Fint = - 71.4 N*Cos 20º = - 67.094 N

the one with the highest speed

explanation:

v=uf/(u-f)

= 5.-10/(5+10) convex lens has negative focal length