4. One day Ali decided to weigh himself in an elevator on a bathroom
scale calibrated in newtons. He did this while the elevator was
stopped and again while it was moving. His mass is 80 kg
the scale read 784 N while the elevator was stationary. Next he
weighed himself while the elevator moved upwards at a constant
speed of 2 m/s. What was his weight at this time?
A. 624 N
B. 944 N
C. 784 N
D. 160 N

the small 0.38-kg slider is known to move from position a to position b along the vertical-plane slot. determine (a) the work done on the body by its weight and (b) the work done on the body by the spring. the distance r = 0.70 m, the spring modulus k = 154 n/m, and the unstretched length of the spring is 0.53 m

explanation:

-reverse card

the tires are rotating at 0.434 rpmlinear speed=45 m/sdiameter=0.550 mradius=0.275 mnow v= rωω= v/rω=45/0.275ω=163.6 rad/sω=163.6 rad/s (1rev/2π rad) (60s/1m)ω=1563 rpm