physics help?

Question

A 6.6 kg mass on a frictionless inclined sur-
face is connected to a 2.4 kg mass. The pulley
is massless and frictionless, and the connect-
ing string is massless and does not stretch.
The 2.4 kg mass is acted upon by an upward
force of 5.6 N, and thus has a downward ac-
celeration of only 4.5 m/s2 .
The acceleration of gravity is 9.8 m/s2 .
What is the tension in the connecting
string? Answer in units of N.

Answer 1

4.5m/s^2 * 2.4kg = 10.8 N of force acting downwards from the string connected to the pulley fulcrum(tip) to the mass that is hanging without support, since the string does not stretch the other tension between the mass on the incline and the pulley fulcrum(tip) is also equal to 10.8N.
Your answer 10.8N

Answer 2

Disagree with your 1st answer.

Since the 2 masses are tied together, they both accelerate at 4.5 m/s^2. By Newton's 2nd, the net force is
Fnet = m*a = 9 kg*4.5 m/s^2
9 kg because the 2 masses are both accelerated.
Fnet = 40.5 N

The weight of the 2.4 kg mass is
W = 2.4 kg*9.8 m/s^2 = 23.5 N

There's an upward force of 5.6 N, call that Fup.

Fnet = W - Fup - T
where T is the tension.

T = W - Fup - Fnet
T = 23.5 N - 5.6 N - 40.5 N
T = - 22.6 N

Since the W is considered here as positive, the negative sign means the tension is an upward force on the hanging mass. & that makes sense.