laws of motion

It is a ques from one of the tests of the test column
Please explain
A man skids from the top of a slide to the bottom in 1 sec There is no friction Nothing else was known What is the height of the ramp

Ans is This problem can't be solved There is additional normal reaction which will cause slowing down of acceleration of the body

What is this additional normal reaction

11 Answers

1
Philip Calvert ·

:O

62
Lokesh Verma ·

The Normal Reaction other than mg

Because the noremal reaction by the ramp will have a component in the vertical direction. So we cannot find the acceleration..

24
eureka123 ·

but motion is along the incline sir..........so dont we have to observe the forces along the icline and perpendicular to it only?????[12]

62
Lokesh Verma ·

So what according to you will be the answer? :O

24
eureka123 ·

Depends on inclination ,I suppose

Let height=h and inclination=θ
=>Length of incline=h/sinθ
accelration due to gravity along incline =gsinθ

=> h/sinθ =gsinθ (1)2/2
=>h=5sin2θ

62
Lokesh Verma ·

yes.. so with the given data, nothing can be said..

we dont know theta!

24
eureka123 ·

yes it cant be solved........[1][1]thats very true.......but the reason given is wrong........[2]

62
Lokesh Verma ·

huh!!

wait i have to draw the fbd...

will you not get

Downward acceleration is mg-Rcosθ = ma

total height is h

so there is a component of normal reaction which is slowing down the acceleration in the downward(vertical) direction!

what is wrong with the satatement!

24
eureka123 ·

maybe I am sleepy or what is happening..................

Isnt the incline fixed?
Isnt motion along incline?
Dont we always observe force along direction of motion?

So why are u drawing components of normal reaction in XY plane??

24
eureka123 ·

sir....plz reply to clear my doubt........[2]

1
Philip Calvert ·

ya ya now got it ...

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