Get Answers to all your Questions

header-bg qa

A block of mass m = 5kg is place on inclined plane of angle \lambda = 37^o. A constant force P is applied of an angle \alpha = 53^o as shown in diagram . What is the value of minimum force of P(in N) , so that the block does not slide down the plane.\left ( g = 10\frac{m}{s^2} \right ).

Option: 1

50


Option: 2

30


Option: 3

40


Option: 4

70


Answers (1)

best_answer

As we learn

Minimum Force to avoid sliding of body down on an inclined plane -

   

P=W \left[\frac{sin(\lambda-\theta)}{cos(\theta+\alpha)} \right ]

P = Pulling force 

\lambda= Angle of Inclination

\theta= Angle of friction

- wherein

For equilibrium 

R+P sin\alpha=W cos\lambda

P cos \alpha+F=W sin \lambda

Use F=\mu R

 

P=\frac{Wsin(\lambda-\theta)}{cos(\theta+\alpha)}

 

 

So For minimum value of force p 

 

 f_{L}=mg \sin \lambda - P \cos \alpha -(i)

R=mg\cos \lambda - P \sin \alpha

f_{L}=\mu R = \mu (mg\cos \lambda -P \sin \alpha )-(ii)

By (i) and (ii)

mg\sin \lambda -p \cos \alpha=\mu(mg\cos \lambda -p \sin \alpha)

p(\cos \alpha -\mu \sin \alpha)=mg\sin\lambda -\mu mg \cos \lambda

p=\frac{mg(\sin \lambda -\mu \cos \lambda)}{\cos \alpha -\mu sin\alpha }

\Rightarrow p=\frac{5*10\left [ \frac{3}{5}-\left [ 0.6*\frac{4}{5} \right ] \right ]}{\left [ \frac{3}{5}-\left [ 0.6*\frac{4}{5} \right ] \right ]}= 50 N

 

Posted by

Rishi

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE