Concepts Of Physics MCQ Edition [Volume 1]PhysicsNewton's Laws of Motion
A particle of mass 50 g travels along a straight line. The variation of its speed with time is displayed in the figure. Determine the force acting on the particle at t = 2 , 4 , and 6 seconds.
Options
- A0.25 N along the motion, zero, and 0.25 N opposite to the motion
- B0.50 N along the motion, zero, and 0.50 N opposite to the motion
- C0.25 N opposite to the motion, zero, and 0.25 N along the motion
- D250 N along the motion, zero, and 250 N opposite to the motion
Correct answer
A. 0.25 N along the motion, zero, and 0.25 N opposite to the motion
Step-by-step solution
The mass of the particle is given as m = 50 g = 0.05 kg . The acceleration a of the particle is the slope of the velocity-time graph, and the force is given by Newton's second law, F = ma . At t = 2 s , the particle is in the time interval 0 to 3 s . The slope of the v-t graph is: a = 15 - 0 3 - 0 = 5 m/s ^2 The force is F = 0.05 5 = 0.25 N . Since the acceleration is positive, the force is along the direction of motion. At t = 4 s , the particle is in the time interval 3 to 5 s . The velocity is constant, so the s