Anonymous
Anonymous asked in Science & MathematicsPhysics · 6 months ago

# A total mass of 80kg rides an elevator. Determine the force exerted on the floor of the elevator when it is accelerating upward at 5.0 m/s2.?

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• Given,

Mass (m) = 80 kg

Acceleration (a) = 5 m/sec²

Force (F) = ?

Here, force of body accelerating against gravitational field. So,

F_Net = m(g+a) = 80(9.81 + 5)

= 1184.8 ≈ 1185 N.

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• For a body accelerating AGAINST a gravitational field (as in this case),

net F = m*(g+a)

so

F = 80kg * (9.8+5.0)m/s² = 1180 N ≈ 1200 N

since the answer SHOULD be to 2 significant digits.

Note the for a body accelerating WITH a gravitational field (such as an elevator beginning its descent),

F = m*(g - a)

Hope this helps!

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• The force on the floor is the sum of the weight of the elevator and the force that causes it to accelerate.

Weight = 80 * 9.8 = 784 N

Force = 80 * 5 = 400 N

Total force = 784 + 400 = 1,184 N

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• Enough to turn people to shoo goo on the floor.

Oh my bad, thought we were talking megaparsecs here.

That is like 120.73 Kg mass weight.

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• Forces on 60kg mass:

R (reaction of elevator floor, up direction)

W (weight of mass, down direction).

Newton's 2nd law:

R - W = R - 80g = 80(5.0)

R = 80 x 9.8 + 80 x 5.0 = 1184N.

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• F = m(g+a) = 80(9.8+5.0) = 1184N

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