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Ipatiy [6.2K]
3 years ago
4

A 38.5 kg man is in an elevator

Physics
1 answer:
Fiesta28 [93]3 years ago
8 0

Answer:

F = m*(g - a) →

a = g - F/m = 0.891 m/s² downward

Explanation:

If elevator was stationary, the normal force of elevator floor on man* would be = mg

mg = (38.5)(9.81) ≈ 378 N.

If elevator is accelerating downward the floor is accelerating away from man and so the normal force will be less than man's weight by: 378 - 343 = 35 N.

<em><u>Hope this helps.</u></em>

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As a science fair project, you want to launch an 800 g model rocket st raight up and hit a horizontally moving target as it pass
fredd [130]

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\sum F_y = ma

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A block is attached to a spring, with spring constant k, which is attached to a wall. it is initially moved to the left a distan
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Answer:

x(t) = d*cos ( wt )

w = √(k/m)

Explanation:

Given:-

- The mass of block = m

- The spring constant = k

- The initial displacement = xi = d

Find:-

- The expression for displacement (x) as function of time (t).

Solution:-

- Consider the block as system which is initially displaced with amount (x = d) to left and then released from rest over a frictionless surface and undergoes SHM. There is only one force acting on the block i.e restoring force of the spring F = -kx in opposite direction to the motion.

- We apply the Newton's equation of motion in horizontal direction.

                             F = ma

                             -kx = ma

                             -kx = mx''

                              mx'' + kx = 0

- Solve the Auxiliary equation for the ODE above:

                              ms^2 + k = 0

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                              s = +/- √(k/m) i = +/- w i

- The complementary solution for complex roots is:

                              x(t) = [ A*cos ( wt ) + B*sin ( wt ) ]

- The given initial conditions are:

                              x(0) = d

                              d = [ A*cos ( 0 ) + B*sin ( 0 ) ]

                              d = A

                              x'(0) = 0

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                              0 = -Aw*sin (0) + Bw*cos(0)

                              B = 0

- The required displacement-time relationship for SHM:

                               x(t) = d*cos ( wt )

                               w = √(k/m)

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