PHYSICS · Subjective · CBSE · Physics · Force and Laws of Motion · Force and Laws of Motion
Problem
A motor-boat is moving eastward on a calm river. At a certain instant, three horizontal forces act on the boat along the same straight line:
• Thrust of the engine: 600N towards the east
• Water drag: 500N towards the west
• Steady wind force: 70N towards the east
(a) Calculate the magnitude and direction of the net horizontal force acting on the boat at this instant.
(b) State the direction of the boat’s acceleration.
(c) The engine is now shut off while the wind and water drag remain unchanged. Identify the new net force and predict the immediate change in the boat’s motion. Give reasons.
(d) A little later the wind also drops to zero, leaving only the water drag acting on the boat. Describe the boat’s motion immediately after the wind stops, citing the principle involved.