Q1. Which of the four drawings is a correct force diagram for this problem (two blocks connected by a string over a pulley, one on an incline and one hanging)?

Background

Topic: Newton's Second Law and Free-Body Diagrams

This question tests your ability to correctly identify all the forces acting on each block in a two-mass system involving a pulley and an inclined plane. Understanding how to draw and interpret free-body diagrams is essential for solving Newton's second law problems.

Key Terms and Formulas

• Free-body diagram: A diagram showing all the forces acting on a single object.

• Tension (): The force transmitted through a string, rope, or cable when it is pulled tight by forces acting from opposite ends.

• Normal force (): The perpendicular contact force exerted by a surface on an object.

• Weight (): The gravitational force acting on an object of mass .

• Newton's Second Law:

Step-by-Step Guidance

1. Identify all the forces acting on each block. For the block on the incline (block 2), consider gravity, the normal force from the plane, and the tension in the string. For the hanging block (block 1), consider gravity and the tension in the string.

2. Remember that the tension is the same throughout the string if the pulley and string are massless and frictionless.

3. For block 2, decompose the gravitational force into components parallel and perpendicular to the incline. The normal force acts perpendicular to the surface, and the tension acts up the incline.

4. For block 1, the tension acts upward, and gravity acts downward.

5. Compare each diagram to see which one correctly represents all these forces with the correct directions and labels. Focus on whether the tension, normal, and weight forces are shown correctly for both blocks.

Try solving on your own before revealing the answer!