Question

Block 1 is placed on top of block 2 with masses 5 kg and 10 kg respectively. A horizontal force P=45 N is applied to block 2 while the other block is tied to a vertical wall. The coefficient of kinetic friction between the moving surfaces is 0.20.
a. draw a fbd for each and identify the action-reaction forces between the blocks
b. determine the tension in the string and the magnitude of the acceleration of block 2.

Answer 1

T is tension
P is applied force
Ff1 frictional force for block1
Ff2 frictional force for block2
W weight

Answer 2

@Callisto pls help...

Answer 3

is my fbd correct?

Answer 4

there's clue thatb a=0.58 m/s^2

Answer 5

your fbd is correct

Answer 6

so for block 1:
summation of x=0
therefore Ff1=T
summation for y=0
N1=W1=49.05N?
then, T= 9.81N?
am i correct?

Answer 7

yes

Answer 8

block 2:
summation for x = 0
P= Ff1+ Ff2
summation of y=o
N2= N1+ W2
N2=147.15 N?
P= 39.24N ?
in this part i am not very sure :(

Answer 9

since the second block is in motion and having an acceleration(which we have to find) there must be some unbalanced force which sets the block 2 in acceleration (read:newton's second law). what you are doing in this case is you are setting opposite forces equal to each other.under this condition there will be no motion at all

Answer 10

we assume that the second block has an acceleration a in the direction in which it is being pulled.as such,the correct equation of motion for block 2 will be