Answer:
A. 4,9 m/s2
B. 2,0 m/s2
C. 120 N
Explanation:
In the image, 1 is going to represent the monkey and 2 is going to be the package. Let a_mín be the minimum acceleration that the monkey should have in the upward direction, so the package is barely lifted. Apply Newton’s second law of motion:

If the package is barely lifted, that means that T=m_2*g; then:

Solving the equation for a_mín, we have:

Once the monkey stops its climb and holds onto the rope, we set the equation of Newton’s second law as it follows:
For the monkey: 
For the package: 
The acceleration a is the same for both monkey and package, but have opposite directions, this means that when the monkey accelerates upwards, the package does it downwards and vice versa. Therefore, the acceleration a on the equation for the package is negative; however, if we invert the signs on the sum of forces, it has the same effect. To be clearer:
For the package: 
We have two unknowns and two equations, so we can proceed. We can match both tensions and have:

Solving a, we have

We can then replace this value of a in one for the sums of force and find the tension T:

Answer: B
Explanation: look at the chart, easy
Potential energy = mgh
Potential energy = 10 x 9.8 x 1.3
Potential energy = 127.4 J
Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that there is no external torque on the system of two twins
so here we will use



Part b)
Since angular momentum is conserved here as there is no external torque
so we will have



Part c)
Work done by both of them = change in kinetic energy
so we have



