Answer:
40N
Explanation:
Since both weights are connected to one string, you can say that the tensions above each are equal to each other.
If you do the sum of forces for the 4kg mass, then the tension comes out to 40N (if we take gravity to be 10m/s²). But that seemed too good to be true, so I decided to do the work for the 7kg mass as well [which included finding the normal force (N) and plugging it into the sum of forces for the 7kg mass] to find that it also gives 40N as the answer.
If I were to put my process into steps:
- Write out the sum of Forces for both masses
- Set them equal to each other to find normal force (because this is the only unknown)
- Calculate and compare the two tensions to see if they are equal
*This all seems to line up perfectly, but do let me know if my answer doesn't match up with what you might find to he the answer later on.
