PSA CLASS 9 QUANTITATIVE REASONING SUBJECT-SCIENCE(PHYSICS) WORKSHEET -1 READ THE FOLLOWING PASSAGE AND ANSWER THE FOLLOWING QUESTIONS Imagine you are pulling a loaded sled with no friction present as shown in the figure. You hold the rope handle of the sled with some angle relative to the ground. You pull as hard as you can and the sled starts to move, but you find that you are getting tired and you still have a significant distance to go. What would you do? One thing is to change the angle at which you pull on the handle of the sled. Should you make the angle larger or smaller? If you pull with smaller angle you will pull the sled more efficiently. This is because the perpendicular force component only can change the direction of the motion. Only the component of a force along the line of motion is effective in changing an object’s speed. So by the work-kinetic energy theorem only the component of force along the line of motion contributes to the work done by the force. To calculate the work done on an object by a force during a displacement , we use only the component of force along the line of object’s displacement. The component of force perpendicular to the displacement does zero work. The work done is given by W=F.scosФ ( s is the displacement) Q1 If angle between force and displacement is 900 then the work will be a.maximum b. positive c.negative d.zero Q2 Work depend on the a.force b.displacement c.angle between force and displacement d. all the above Q3.The work done to diplace a body upto 10m by a force of 10N,when the angle between force and displacement is 300 ,would be a. 96.5J b. 86.5 J ANSWERS---1. 2. c.105.6J d.75.6 J 4 READ THE FOLLOWING PASSAGE AND ANSWER THE QUESTION Q1. .Q2. Q3. Q4. ANSWERS 1 2 3 4