7. (10 points) Determine the force $F$ that needs to be applied to the plate to move a load of mass $m=3$ kg, lying on a horizontal smooth surface. All pulleys are smooth and weightless. The acceleration due to gravity $g=10 \mathrm{m} /$ kg.

![](https://cdn.mathpix.com/cropped/2024_05_06_cb5516e3c2a397a958cdg-7.jpg?height=434&width=622&top_left_y=2164&top_left_x=820)
Answer: $60 \mathrm{H}$.

![](https://cdn.mathpix.com/cropped/2024_05_06_cb5516e3c2a397a958cdg-8.jpg?height=417&width=585&top_left_y=208&top_left_x=838)

We get: $F=4 T=2 \mathrm{mg}=2 \cdot 3 \cdot 10=60 \mathrm{H}$.