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    sophia jain's Avatar
    sophia jain Posts: 2, Reputation: 1
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    #1

    Feb 8, 2014, 02:46 AM
    Work power energy
    A block of mass 2 kg is pulled up on a smooth incline making angle 30 degrees with horizontal . If block moves with an acceleration of 1 m/s2 , find
    a) Power delivered by the pulling force at a time 4 sec after motion starts
    b)average power deliverd after 4 sec the motion starts
    ***MY DOUBT
    I am very weak in kinematics , so please explain that the formula s=ut+1/2at^2 gives displament or distance. And if it gives displacement then it will only give the length of base of the incline and not d length of hypotenuse which if needed?
    ebaines's Avatar
    ebaines Posts: 12,131, Reputation: 1307
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    #2

    Feb 8, 2014, 05:33 AM
    The formula gives distance travelled in the direction of the acceleration and velocity . But that's not the formula you want to use to solve this. First find the force being applied to the block in the direction of the ramp. Then calculate the velocity of the block at t t= 4 seconds. Finally recall that power equals force times velocity.
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