Examora
|
MCQ & Notes
Back to Home
NCERT Solutions for Class 11 Physics Ch-3: Motion in a Plane
NCERT Solutions for Class 11 Physics Chapter 3 Motion in a Plane deals with vector quantities and their operations, along with two-dimensional motion such as projectile motion and uniform circular motion.
Overview of Topics & Subtopics
Important Questions and Answers
Q1: What is the difference between a scalar and a vector quantity? Give one example of each.
Answer: A scalar quantity has only magnitude (e.g., mass, temperature, speed), while a vector quantity has both magnitude and direction (e.g., displacement, velocity, force). Mass is an example of a scalar, and velocity is an example of a vector.
Q2: Derive the expression for the maximum height and time of flight of a projectile launched at an angle θ with initial speed u.
Answer: For a projectile launched with speed u at angle θ to the horizontal, the maximum height is H = (u² sin²θ)/(2g), and the total time of flight is T = (2u sinθ)/g, where g is the acceleration due to gravity, derived by analyzing the vertical component of motion independently from the horizontal component.
Q3: What is the formula for the horizontal range of a projectile, and at what angle is the range maximum?
Answer: The horizontal range of a projectile is given by R = (u² sin2θ)/g. The range is maximum when sin2θ = 1, i.e., when the angle of projection θ = 45°.
Q4: What is centripetal acceleration, and what formula gives its magnitude for uniform circular motion?
Answer: Centripetal acceleration is the acceleration directed towards the centre of a circular path that keeps an object moving in a circle at constant speed. Its magnitude is given by ac = v²/r, where v is the speed and r is the radius of the circular path.
Q5: Why does a projectile follow a parabolic trajectory?
Answer: A projectile follows a parabolic path because its horizontal motion (constant velocity, no acceleration) and vertical motion (uniform acceleration due to gravity) are independent of each other; when these two perpendicular motions are combined, the resultant trajectory traced out is a parabola.
Continue learning with this chapter:
Notes, MCQs and test for the same chapter
Read More & Chapter Resources
These short notes are designed for quick revision. Read the main points once, then use the related material below to practise the same chapter. Revising a concept and checking it with questions can make your preparation more focused.