302 - Mechanics part 1 Questions Answers

sir

there is a statement ie

FRICTION IS SELF ADJUSTABLE   , is it right or not ??  The problem is only static frictn is self adjustable , so wat shld be the ans for only frictn ??

Asked By: SARIKA
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Joshi sir comment

in a general way the statement is correct

Physics >> Mechanics part 1 >> Kinematics Medical Exam

the min no. of non coplanar and non zero vectors of unequal magnitude which can give zero resultant is _________??

Asked By: SARIKA
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Joshi sir comment

four

let three are i, j, k then fourth will be -(i+j+k)

Physics >> Mechanics part 1 >> Kinematics Medical Exam

if y= 50 / [(x-5)2 +5]2  then maximum value of y will be??     

      

Asked By: SARIKA
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Joshi sir comment

let z = [(x-5)2 +5]

then dz/dx = 2(x-5)

compare it to 0 we get x = 5

so for x = 5, z will be minimum and so y will be max for that x

put x= 5 and get answer 

A particle has initial velocity of y = 3i+ 4j and a constant force F = 4i -3j acts on it. Then what will be the path followed by the particle?

Asked By: VIKRAM
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Joshi sir comment

acceleration is constant and initial velocity is perpendicular to it because dot product of two given vectors is 0 so this is the case equivalent to a particle thriwn from the top of a building horizontally under gravity so path will be parabolic

if you want the equation of path then reply

A block of mass 100 g is moved with a speed of 5 m/s at the highest point in a closed circular tube of radius 10 cm kept in vrtical plane.The cross section of the tube is such that the block just fits in it.The block makes several oscillations inside the tube and finally stops at the lowest point. Find the work done by the tube on the block.

Asked By: SUBHASH
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Joshi sir comment

Total energy is lost so K E will be the work done

A ball is dropped from the top of the tower of height h. It covers a distance h/2 in the last second of its motion. How long does the ball remain in air?

Asked By: GAUTAM SAGAR
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Joshi sir comment

let total time of flight = t

so h = gt2/2 and

h/2 = gt-(g/2)

so gt2/4 = gt-(g/2)

or t2/4 = t -(1/2)

now solve 

What is the minimum coefficient of friction for a solid sphere to roll without slipping on an inclined plane of inclination θ?

Asked By: SWATI KAPOOR
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Joshi sir comment

friction f = mgsinθ/[1+(mr2/I)]

solve for sphere and compare to μmgcosθ

 

A particle moving with constant acceleration covers a distance of 30m in the 3rd second. it covers a distance of 50m in the 5th  second. What is the acceleration of the particle?

Asked By: GAUTAM SAGAR
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Joshi sir comment

use formula for the distance covered in a particular second 

st = u+at-(a/2)

A particle is moving with a velocity of 10m/s due east. In One second its velocity changes to 10m/s due west. If the particle is uniformly accelerated, the change in velocity will be directed as

Asked By: GAUTAM SAGAR
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Joshi sir comment

let east is i

then velocity change = -10i-10i = -20i

A  ball is dropped from a height h reaches the ground in time T. What is its height at time T/2

Asked By: GAUTAM SAGAR
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Joshi sir comment

h = 1/2 gT2

in T/2 time h' = 1/2 gT2/4 = 1/8 gT2

so height from ground = h-h'

solve?

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