A block of mass 10 kg, moving in x direction with a constant speed of 10 ms-1, is subjected to a retarding force F = 0.1 x J/m during its travel from x = 20 m to 30 m. Its final KE will be:

  • Option 1)

    275 J

  • Option 2)

    250 J

  • Option 3)

    475 J

  • Option 4)

    450 J

 

Answers (2)

As we discussed in

Net work done by all the forces give the change in kinetic energy -

W=frac{1}{2}mv^{2}-frac{1}{2}mv{_{0}}^{2}

W= k_{f}-k_{i}

- wherein

m=mass : of: the: body

v_{0}= initial: velocity

v= final: velocity

 

 

 

Definition of work done by variable force -

W=int vec{F}cdot vec{ds}

- wherein

vec{F} is variable force and vec{ds} is small displacement

 

 k_{i}=\frac{1}{2}m{v_{i}}^{2}=\frac{1}{2}\times 10\times \left ( 10 \right )^{2}=500J

w= \int_{x_{1}}^{x_{2}}f_{r}.dx=\int_{20}^{30}-0.1x dx= -0.1\left [ \frac{x^{2}}{2} \right ]^{30}_{20}= -0.1\left [ \frac{900-400}{2} \right ]= -25J

w= k_{f}-k_{i}=k_{f}=w+k_{i}

-25 J+500 J = 475 J


Option 1)

275 J

Incorrect Option

Option 2)

250 J

Incorrect Option

Option 3)

475 J

Correct Option

Option 4)

450 J

Incorrect Option

Most Viewed Questions

Preparation Products

Knockout NEET 2024

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 40000/-
Buy Now
Knockout NEET 2025

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 45000/-
Buy Now
Knockout NEET 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
Buy Now
Knockout NEET 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-
Buy Now
Test Series NEET 2021

Chapter/Subject/Full Mock Tests for NEET, Personalized Performance Report, Weakness Sheet, Complete Answer Key,.

₹ 6999/- ₹ 2999/-
Buy Now
Boost your Preparation for NEET 2021 with Personlized Coaching
 
Exams
Articles
Questions