Question

A 50-kg student stands on a scale in an
elevator. At the instant the elevator has a
downward acceleration of1.0 m/s2 and an
upward velocity of 3.o m/s, the scale reads
approximately
​

Answer 1

Answer:

Sum of the vertical forces on the student (up is positive) = m*a

What are the vertical forces? Weight, which acts down (negative), and the normal force from the scale, which acts up (positive).  The normal force is what the scale reads.

m*a = N - m*g

Solve for N

N = m*(a+g)

*** Notice velocity isn't even part of the solution?  We get to ignore it! ***

Plug in the numbers.  Remember we declared "up is positive" and the elevator is accelerating down, so the acceleration is negative.  With the acceleration due to gravity, the direction was already taken into account as a negative in the m*a equation.  Just input it in as a positive number.

N = 50 kg * (9.8 m/s^2 - 1 m/s^2) = 440 N <---

That's what I got.  Hope the explanation helped

Explanation:

Answer 2

Answer:

450 N

Explanation:

Elevator physics: FN represents the scale reading. ΣF = ma; FN – mg = ma, or FN = m(g + a). The velocity of the elevator is irrelevant.

hope will be helpful