Laws of Motion

Step 1: Find the friction force for each block
The friction force is given by: F‌friction ‌=µk×m×g
For block A (mass =2kg ):
FKA=0.3×2×10=6N
For block B (mass =4kg ):
FKB=0.3×4×10=12N
Step 2: Find the net force on each block
The net force is the applied force minus friction:
For block A :
FA=20−6=14N
For block B :
FB=20−12=8N
Step 3: Find the acceleration of each block
Use a=‌

Fnet

m

for each block.
For block A :
aA=‌

14

2

=7m∕s2
For block B :
aB=‌

8

4

=2m∕s2
Step 4: Find the ratio of accelerations ‌

aA

aB

=‌

7

2

So, the ratio is 7:2.