NCERT Class 9 Science Chapter 6 How Forces Affect Motion Solutions
NCERT Class 9 Science Chapter 6 How Forces Affect Motion Solutions Think It Over (Page No. 94) 1. Why does a canoe move forward when the canoeist pushes water backwards with their paddle and why does it move faster when they push harder? Answer: By Newton’s 3rd Law, when the paddle pushes water backward , water pushes the paddle forward with equal and opposite force, moving the canoe forward. Pushing harder increases this reaction force, so the canoe moves faster (Newton’s 2nd Law: F = ma). 2. Suppose the same canoeist uses the same paddle force in two different canoes, one empty and one carrying another passenger. In which case will the canoe move faster? Answer: The empty canoe moves faster. Same force, but less mass = more acceleration (a = F/m). The canoe with a passenger has more mass, so acceleration is less. Pause and Ponder (Page No. 97) 1. A weightlifter lifts a barbell (Fig. 6.8). List two forces that are acting on the barbell. Are these forces balanced if the weight...