Class 9 Physics Question Answer in 90 to 120 words.
Chapter 7
5. (2) An athlete completes one round of circular track of diameter 200m in 40 s.
What will be the distance covered and the displacement at the end of 2min 20s?
Chapter 8
2. Write newton's second law of motion and derive F = ma
4. Explain Galileo's thinking about motion
__________________________________
* Satisfied Answer
* under 120 words
* verified answer and Moderator Answer or Genius Answer
Answers & Comments
Explanation:
Chapter 7:
5. An athlete completes one round of a circular track with a diameter of 200 meters in 40 seconds. To find the distance covered in 2 minutes and 20 seconds (or 140 seconds), we first calculate the time taken for one round: 40 seconds. Then, we find the number of rounds in 140 seconds, which is 140 / 40 = 3.5 rounds. So, the distance covered is 3.5 times the circumference of the track, which is π times the diameter. Therefore, the distance covered is 3.5 * π * 200 meters, and the displacement at the end is zero since the athlete returns to the starting point.
Chapter 8:
2. Newton's second law of motion states that the force acting on an object is equal to the mass of the object multiplied by its acceleration, or F = ma. To derive this equation, consider a body of mass 'm' subjected to a force 'F,' which causes an acceleration 'a.' According to Newton's first law, the body will move with a constant velocity unless acted upon by a net force. Therefore, the net force 'F' causes a change in velocity 'Δv' over a time interval 'Δt,' which is equal to 'aΔt.' Using the definition of acceleration (a = Δv/Δt) and rearranging, we get F = m * (Δv/Δt), which simplifies to F = ma.
4. Galileo's thinking about motion was revolutionary. He believed that all objects fall at the same rate regardless of their mass, disproving Aristotle's earlier belief that heavier objects fall faster. Galileo also proposed the concept of inertia, stating that objects tend to remain at rest or in uniform motion unless acted upon by an external force. He conducted experiments, like rolling balls down inclines, to support his ideas. These insights laid the foundation for Newton's laws of motion and our modern understanding of how objects move. Galileo's work was pivotal in the scientific revolution and reshaped our understanding of physics.
Verified answer
:) (:
happy?
have a great day ✌