Answer:
3.26 m/s²
Step-by-step explanation:
Draw a free body diagram. There are four forces:
Weight force mg pulling down,
Normal force N pushing up,
Applied force F pushing right,
Friction force Nμ pushing left.
Sum of forces in the y direction:
∑F = ma
N − mg = 0
N = mg
Sum of forces in the x direction:
∑F = ma
F − Nμ = ma
F − mgμ = ma
Plug in values:
102 N − (2.8 kg + 12.8 kg) (9.8 m/s²) (0.335) = (2.8 kg + 12.8 kg) a
a = 3.26 m/s²