Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • The escape speed of a projectile on the earth’s surface is 11.2 km s^–1. A body is projected out with thrice this speed. What is the speed of the body far away from the earth? Ignore the presence of the sun and other planets.

Q: 8.18 The escape speed of a projectile on the earth’s surface is  \small 11.2\hspace {1mm}km\hspace {1mm}s^-^1. A body is projected out with thrice this speed. What is the speed of the body far away from the earth? Ignore the presence of the sun and other planets.

Answers (1)

best_answer

 Let us assume the speed of the body far away from the earth is  v_f.

Total energy on earth is :

                                                =\ \frac{1}{2}mv_p^2\ -\ \frac{1}{2}mv_{esc}^2

And the total energy when the body is far from the earth is :

                                                 =\ \frac{1}{2}mv_f^2                         

(Since the potential energy at far from the earth is zero.)

We will use conservation of energy :  - 

                                \frac{1}{2}mv_p^2\ -\ \frac{1}{2}mv_{esc}^2\ =\ \frac{1}{2}mv_f^2

or                                          v_f\ =\ \sqrt{\left ( v_p^2\ -\ v_{esc}^2 \right )}

or                                                  =\ \sqrt{\left ( \left ( 3v_{esc} \right )^2\ -\ v_{esc}^2 \right )}

or                                                  =\ \sqrt{8}v_{esc}

 or                                                 =\ 31.68\ Km/s

Posted by

Devendra Khairwa

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads

Similar Questions

Trending Articles/News

anam-khan

CBSE 10th, 12th practical exams 2025 begin; instructions for students, schools
anam-khan

CBSE Single Girl Child Scholarship 2024: Registration extended till January 10; eligibility criteria, amount
anam-khan

CBSE wants international boards reined in; letter to education ministry seeks directions for AIU

Latest Question