Answer:
12N
Explanation:
Suppose the string mass is negligible, the total mass of the 2 block system is 6 + 9 = 15 kg
So the acceleration of the system when subjected to 30N force is
a = F / M = 30 / 15 = 2 m/s2
So both blocks would have the same acceleration, however, the force acting on the 6kg block would have a magnitude of
f = am = 2 * 6 = 12N
This is the tension in the string between the blocks
Answer:


Explanation:

Required
The units of A and B
From the question, we understand that:

This implies that each of
and
will have the same unit as 
So, we have:


The unit of t is (s); So, the expression becomes

Divide both sides by 


Answer:
Due to the resistance of air, a drag force acts on a falling body (parachute) to slow down its motion. Without air resistance, or drag, objects would continue to increase speed until they hit the ground. The larger the object, the greater its air resistance. Parachutes use a large canopy to increase air resistance. Also, Once the parachute is opened, the air resistance overwhelms the downward force of gravity. The net force and the acceleration on the falling skydiver is upward. An upward net force on a downward falling object would cause that object to slow down. The skydiver thus slows down. Sorry if not helpful.