explain to me this...Please

[al3ck]

A passenger stands on a scale which is inside an elevator. If the scale reads 110 pounds when the elevator is at rest, what would it read when the elevator begins to accelerate upwards at 3 ft/sec2

115 pounds
120 pounds
130 pounds
135 pounds

same magnitude as the normal force of the scale upward on the person.

Now consider the case of an upward acceleration of 3 ft/sec2. The net force on the person is now N - mg = N - 110 = ma, where N is the normal force of the scale upward on the person and we've used the fact that the person's weight is mg = 110. So we have a reading on the scale of N = 110 + ma. From mg = 110, we have m = 110/g = 110/32 (g = 32 ft/s2) . Thus, N = 110 + 3(110/32) , so N = 120 pounds.
Where the the 32 come from!!!

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[Isoprop]

A passenger stands on a scale which is inside an elevator. If the scale reads 110 pounds when the elevator is at rest, what would it read when the elevator begins to accelerate upwards at 3 ft/sec2

115 pounds
120 pounds
130 pounds
135 pounds

same magnitude as the normal force of the scale upward on the person.

Now consider the case of an upward acceleration of 3 ft/sec2. The net force on the person is now N - mg = N - 110 = ma, where N is the normal force of the scale upward on the person and we've used the fact that the person's weight is mg = 110. So we have a reading on the scale of N = 110 + ma. From mg = 110, we have m = 110/g = 110/32 (g = 32 ft/s2) . Thus, N = 110 + 3(110/32) , so N = 120 pounds.
Where the the 32 come from!!!

g = 9.8 m/s^2
each meter is 3.28 feet
g = 9.8 m/s^2 * 3.28 ft/m = 32 ft/s^2

 

[ChubbyChaser]

Yeah 32 is the constant for acceleration.

 

[al3ck]

Ok i got it, so stupid i didn't know what happen......thanx