Download Class 9 Science Worksheets for Chapter 08 Force and Laws of Motion
Explore reliable practice materials for Chapter 08 Force and Laws of Motion tailored for Class 9 learners. Utilizing these Science worksheets ensures thorough preparation and strengthens problem-solving speed for upcoming school assessments.
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Access the complete worksheet PDF for Chapter 08 Force and Laws of Motion below. Regular practice with these targeted questions builds familiarity with standard exam patterns and helps secure higher marks in final Science evaluations.
Short Answer Questions
Question. Akhtar, Kiran and Rahul were riding in a motorocar that was moving with a high velocity on an expressway when an insect hit the windshield and got stuck on the
windscreen. Akhtar and Kiran started pondering over the situation. Kiran suggested that the insect suffered a greater change in momentum as compared to the change in momentum of the motorcar (because the change in the velocity of the insect was much more than that of the motorcar). Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect.
And as a result the insect died. Rahul while putting an entirely new explanation said that both the motorcar and the insect experienced the same force and a change in their momentum. Comment on these suggestions.
Answer : According to the law of conservation of momentum:
Momentum of the car and insect system before collision = Momentum of the car and insect system after collision Hence, the change in momentum of the car and insect system is zero.
The insect gets stuck on the windscreen. This means that the direction of the insect is reversed. As a result, the velocity of the insect changes to a great amount.
On the other hand, the car continues moving with a constant velocity. Hence, Kiran's suggestion that the insect suffers a greater change in momentum as compared to the car is correct. The momentum of the insect after collision becomes very high because the car is moving at a high speed. Therefore, the momentum gained by the insect is equal to the momentum lost by the car.
Akhtar made a correct conclusion because the mass of the car is very large as compared to the mass of the insect.
Rahul gave a correct explanation as both the car and the insect experienced equal forces caused by the Newton's action-reaction law. But, he made an incorrect statement as the system suffers a change in momentum because the momentum before the collision is equal to the momentum after the collision.
Question. How much momentum will a dumbbell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 m s-2.
Answer :
Mass of the dumbbell, m = 10 kg
Distance covered by the dumbbell, s = 80 cm = 0.8 m
Acceleration in the downward direction, a = 10 m/s2
Initial velocity of the dumbbell, u = 0
Final velocity of the dumbbell (when it was about to hit the floor) = v
According to the third equation of motion:
v2= u2 + 2as
v2= 0 + 2 (10) 0.8
v= 4 m/s
Hence, the momentum with which the dumbbell hits the floor is
= mv
= 10 × 4 kg m s-1
= 40 kg m s-1
Question. An object experiences a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? If yes, state the conditions that must be placed on the magnitude and direction of the velocity. If no, provide a reason.
Answer : Yes. Even when an object experiences a net zero external unbalanced force, it is possible that the object is travelling with a non-zero velocity. This is possible only when the object has been moving with a constant velocity in a particular direction.
Then, there is no net unbalanced force applied on the body. The object will keep moving with a non-zero velocity. To change the state of motion, a net non-zero external unbalanced force must be applied on the object.
Question. Why is it advised to tie any luggage kept on the roof of a bus with a rope?
Answer : When the bus accelerates and moves forward, it acquires a state of motion.
However, the luggage kept on the roof, owing to its inertia, tends to remain in its state of rest. Hence, with the forward movement of the bus, the luggage tends to remain at its original position and ultimately falls from the roof of the bus. To avoid this, it is advised to tie any luggage kept on the roof of a bus with a rope.
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Practice Worksheet and Study Resources for Class 9 Science Chapter 08 Force and Laws of Motion
Chapter Practice Questions for Class 9 Science
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FAQs
You can download the teacher-verified PDF for CBSE Class 9 Science Force and Laws of Motion Worksheet Set 04 from StudiesToday.com. These practice sheets for Class 9 Science are designed as per the latest CBSE academic session.
Yes, our CBSE Class 9 Science Force and Laws of Motion Worksheet Set 04 includes a variety of questions like Case-based studies, Assertion-Reasoning, and MCQs as per the 50% competency-based weightage in the latest curriculum for Class 9.
Yes, we have provided detailed solutions for CBSE Class 9 Science Force and Laws of Motion Worksheet Set 04 to help Class 9 and follow the official CBSE marking scheme.
Daily practice with these Science worksheets helps in identifying understanding gaps. It also improves question solving speed and ensures that Class 9 students get more marks in CBSE exams.
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