Maharashtra Board Class 11 Physics Solution Chapter 3 – Motion in a Plane
Balbharati Maharashtra Board Class 11 Physics Solution Chapter 3: Motion in a Plane. Marathi or English Medium Students of Class 11 get here Motion in a Plane full Exercise Solution.
Std |
Maharashtra Class 11 |
Subject |
Physics |
Chapter |
3 |
Chapter Name |
Motion in a Plane |
1.) Choose the correct option.
i) An object thrown from a moving bus is on example of
(A) Uniform circular motion
(B) Rectilinear motion
(C) Projectile motion
(D) Motion in one dimension
Answer- C
An object thrown from a moving bus follows projectile motion.
ii) For a particle having a uniform circular motion, which of the following is constant
(A) Speed (B) Acceleration
(C) Velocity (D) Displacement
Answer-A
By definition of uniform circular motion it is the motion in which speed is constant.
iii) The bob of a conical pendulum under goes
(A) Rectilinear motion in horizontal plane
(B) Uniform motion in a horizontal circle
(C) Uniform motion in a vertical circle
(D) Rectilinear motion in vertical circle
Answer- B
The bob of a conical pendulum under goes uniform circular motion in horizontal motion.
iv) For uniform acceleration in rectilinear motion which of the following is not correct?
(A) Velocity-time graph is linear
(B) Acceleration is the slope of velocity time graph
(C) The area under the velocity-time graph equals displacement
(D) Velocity-time graph is nonlinear
Answer-D
For uniform acceleration in rectilinear motion Velocity-time graph is linear.
2.) Answer the following questions.
i) Separate the following in groups of scalar and vectors: velocity, speed and displacement, work done, force, power, energy, acceleration, electric charge, angular velocity.
Answer-
Scalars- speed, work done, energy, power, electric charge.
Vectors- velocity, displacement, force, acceleration, angular velocity.
ii) Define average velocity and instantaneous velocity. When are they same?
Answer-
Average velocity: This is defined as the displacement of the object to thethe time interval taken by object to complete the motion.
iii) Define free fall.
Answer- motion of body under only gravitational force is called free fall.
iv) If the motion of an object is described by x = f (t) write formulae for instantaneous velocity and acceleration.
Answer-
For instantaneous velocity for motion x = f (t) is given by,
It can be seen from this equations that motion along x direction is completely controlled by x components of velocity and acceleration independent on y direction. While motion along y-direction is completely controlled by y-components of velocity and acceleration independent on x-direction. This shows that these two equations are independent of each other.
vi) Derive equations of motion graphically for a particle having uniform acceleration, moving along a straight line.
Answer-
Consider velocity time graph shown in figure
1.) Consider an object traveling along AB at x=0 at t=0. Let initial velocity be u and at time t is v.
As slope of velocity time graph gives acceleration of motion hence Slope of line AB gives acceleration of motion. Thus,
viii) Show that the path of a projectile is a parabola.
Consider a body is projected with velocity u at an angle of θ as shown in figure. Then,
Horizontal component of ux= u x´sin (θ).
Vertical component of u, uy= u cos (θ).
This projectile motion is under gravitational acceleration only and it acts in vertically downward direction only hence
Acceleration on horizontal, a_{x}=0
Acceleration on vertical, a_{y}=−g
Using definition of velocity,
X=u_{x}´x t
X=ucosθ´t
t=X/ucosθ………………….(1)
using law of motion for y direction as in y direction acceleration is constant.