Skip to content
Login Register

#relative motion

4 public questions tagged with this topic.

PHYSICS

A man runs at 5 m/s towards a wall and throws a ball at 15 m/s towards the wall when 20 m away. If the ball rebounds at

Given: A man runs at 5 m/s towards a wall and throws a ball at 15 m/s towards the wall when 20 m away. If the ball rebounds at 10 m/s, when does it return to the man? (Take wall as origin) These values define the system as per NCERT data. Formula: Relative speed towards wall = 15 + 5 = 20 m/s. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Time to hit wall: t_1 = 20/20 = 1 s . Man’s position = 5 · 1 = 5 m from wall. Ball rebounds at 10 m/s, relative speed = 10 - 5 = 5 m/s towards man. Time to return: t_2 = 5/5 = 1 s . Total time = 1 + 1 = 2 s

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Units and Measurements and Physical World, Topic: Dimensional analysis and fundamental principles.

View Details
Uniform Acceleration and Graphical Analysis

A rocket is launched vertically at 60m/s from the ground. After 5s, a second rocket is launched at 45m/s. How long after

First: y1=60t−5t2, second: y2=45(t−5)−5(t−5)2. As per NCERT Chapter 3, equations v=u+at, s=ut+½at², v²=u²+2as describe uniformly accelerated motion. Applying correct signs and units gives 5 s as the result, so option B is correct.

Ref: NCERT Class 11 Physics > Chapter 3: Motion in a Straight Line > Topic: Uniform Acceleration and Graphical Analysis

View Details
Motion in a Straight Line - Advanced Problems

Two stones are released from a height of 98m, 1s apart. How long after the second stone is released do they meet? (Take

Stone 1: y1=12⋅9.8⋅(t+1)2. As per NCERT Chapter 3, equations v=u+at, s=ut+½at², v²=u²+2as describe uniformly accelerated motion. Applying correct signs and units gives 12 as the result, so option A is correct.

Ref: NCERT Class 11 Physics > Chapter 3: Motion in a Straight Line > Topic: Motion in a Straight Line - Advanced Problems

View Details