Question

find the gravitational field at a point P at a distance a from one end of arod of Lambda = 2x​

Answer 1

Answer

Correct option is

B

a(l+a)

GmM

​

 

Assume a element of mass dm at a distance X from mass m  

Force due to small element of rod  dF=  

X  

2

 

Gdm×m

​

 

F=∫  

a

a+l

​

 

X  

2

 

Gdm×m

​

 

dm=  

l

M

​

dx

F=∫  

a

a+l

​

 

lX  

2

 

GM×m

​

dx

F=  

l

GM×m

​

[  

X

1

​

]  

a

a+l

​

 

F=  

l

GM×m

​

[  

a+l

1

​

−  

a

1

​

]  

a

a+l

​

 

F=  

a(l+a)

GM×m

​