A block of mass 6kg is placed on a horizontal floor. when it is pulled by a force of 30N, it moves with a constant speed of 15 m/s.?

(a) calculate the resultant force?

(b) calculate the frictional force?

(c) the block is now pulled with a force of 35N for 3s calculate

(i) the acceleration?

(ii) the speed of the block after 3s?

please help!

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  • 7 years ago
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    Ooops, I didn't see question c till submiting a and b. Pretend this is at the bottom.

    c. Fres was 0 when applied force was 30. So now Fres=5N.

    i. Fres = mass*acceleration

    Solve for accel.

    ii. Use the kinematic formula

    Vf = Vi + a*t

    where Vi is initial velocity = 0, a is accel, and t is 3 s.

    _________________________________

    I started here.

    Constant speed, so acceleration is zero.

    Fres = mass * acceleration

    That is Newton's 2nd law

    Fres = 6 kg * 0 = 0

    Fres is the resultant of forces on the block.

    Fres = applied force + friction

    You know from above that Fres is zero and applied force is given as 30N. Plug 'em in and solve for friction.

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