# physics

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2. a body of mass 20kg is released from rest t the top of a rough slope which is inclined at 30 degrees to the horizontal.six seconds later the body has a velocity of 21 m.s down the slope. find the resistance to motion in newtons experienced by the body?

• physics -

Fb=mg = 20kg * 9.8N/kg = 196N @ 30deg.

Fp = 196*sin30 = 98N = Force parallel
to plane.

a=(Vf-Vo) / t = (21-0) / 6 = 3.5m/s^2.

Fn = Fp-Ff = ma,
98 - Ff = 20 * 3.5,
Ff = 28N = Force of friction.

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