Question

Two athletes in a team, A and B, are practicing to compete in a boat race. Athlete A has a mass of 70 kg, B has a mass of 75 kg, and the boat has a mass of 20 kg. Athlete A can exert an average force of 400 N and B an average force of 420 N on the boat using the paddles. During paddling, the magnitude of the water resistance on the boat is 380 N. Calculate the acceleration of the boat.

• A. $2.67m/s^2$
• B. $3m/s^2$
• C. $-2.67m/s^2$
• D. $26.7m/s^2$

Answer 1

The correct option is A $2.67m/s^2$

Total mass = Mass of (A + B+ boat) $=70+75+20=165kg$

Net force $=400N+420N-380N=440N$ in the forward direction

We know $F=mass\times acceleration$

$\Rightarrow 440=165\times a$

$440=165\times a$

$\therefore a=\frac{440}{165}=2.67m/s^2$