1. The weight in the following diagram has a mass of 0.750 kg and the cart has a mass of 0.52 kg. There is a friction force of 2.1 N acting on the cart. What is the tension in the string?

a. 4.4 N
b. 4.3 N
c. 4.1 N
d. 4.2 N

2. An 8.5 kg block is attached to a weight. The coefficient of static friction between the block and the table is 0.71. What is the minimum mass required for the weight in order to start the block in motion?
a. 6.0 kg
b. 7.0 kg
c. 4.0 kg
d. 5.0 kg

For both problems, there is a diagram with a pulley between the weight and the block/cart

For #1 I got 4.04N, but that isn't an option. I used f=ma where f=2.1N and m=0.52kg

For #2 i think the answer is A.

1 answer

See
http://www.jiskha.com/display.cgi?id=1496429854

Please show your attempt for part 2.
You need to draw separate FBD (free body diagrams) for the block and weight. Also, please describe the diagram in words, i.e. confirm whether the weight is free-hanging.