@Rajath Krishna R
–
@Rajath there are two ways of doing this. Actually both are different approaches having same meaning.
If you are familiar with basic integration you can try integrating the net force wrt time to get the change in momentum hence you can find the velocity.
Or you can first try to sketch the graph of net force versus time and find it's area b/w t=3 to t=10.(Both are same methods actually as integration is nothing but area bounded). The area gives you the change in momentum therefore you can calculate velocity.
But remember that we are not finding area under the graph in the question. We have to sketch our own graph of net force (Just the given graph pull it downwards by 120 )

if you do that properly the area comes out to be 480.
hence the velocity would be 480/20= 24 m/s.
–
Saurabh Dubey
·
3 years, 10 months ago

Log in to reply

Is the answer 49 m/s ? (assuming g=10 m/s^2)
–
Saurabh Dubey
·
3 years, 10 months ago

@Rajath Krishna R
–
You need the value of g to know when will the body start moving (3 seconds in this case)
Because for the body to move, F>= 0.6Mg i.e. F>=120. Hence the body starts moving after 3 secs.
–
Saurabh Dubey
·
3 years, 10 months ago

This is the question........
A 20 kg block is originally at rest on a horizontal surface for which the coefficient of
friction is 0.6. If a horizontal force is applied such that it varies with time as shown. Determine
the speed of block in 10 sec.
–
Rajath Krishna R
·
3 years, 10 months ago

## Comments

Sort by:

TopNewestOh!! i got the question wrong!! the answer must be 24 m\s. (with g=10 m\s^2) – Saurabh Dubey · 3 years, 10 months ago

Log in to reply

– Rajath Krishna R · 3 years, 10 months ago

yeah its right......how did u do it..................Log in to reply

if you do that properly the area comes out to be 480. hence the velocity would be 480/20= 24 m/s. – Saurabh Dubey · 3 years, 10 months ago

Log in to reply

Is the answer 49 m/s ? (assuming g=10 m/s^2) – Saurabh Dubey · 3 years, 10 months ago

Log in to reply

– Rajath Krishna R · 3 years, 10 months ago

what's the need of g here????Log in to reply

Mg i.e. F>=120. Hence the body starts moving after 3 secs. – Saurabh Dubey · 3 years, 10 months agoLog in to reply

– Rajath Krishna R · 3 years, 10 months ago

yeah i forgot about it.............I too did the same way...Log in to reply

Log in to reply

– Rajath Krishna R · 3 years, 10 months ago

noop.....................Log in to reply

This is the question........ A 20 kg block is originally at rest on a horizontal surface for which the coefficient of friction is 0.6. If a horizontal force is applied such that it varies with time as shown. Determine the speed of block in 10 sec. – Rajath Krishna R · 3 years, 10 months ago

Log in to reply

– Aravind Kukkila · 3 years, 10 months ago

is the answer 58.8 m/s ?Log in to reply

– Rajath Krishna R · 3 years, 10 months ago

noop.....Log in to reply

– Aravind Kukkila · 3 years, 10 months ago

6 m/s ?????Log in to reply

ohhhh very small pic – Rajath Krishna R · 3 years, 10 months ago

Log in to reply