If 10 meter long crane is used to move a rock horizontally at a construction site. when lifting the crane, the cable is continually extended to maintain the rock at the same height with the height of the crane pivot so that the rock moves only horizontally. if the crane is lifted with an angular speed dθ/dt = 1/4 rad/s where θ is an angle between the crane and the ground and t represents time, how fast the rock is moving toward the crane base when the cable is 8 meter

•• al and bert are jogging side-by-side on a trail in the woods at a speed of 0.75 m/s. suddenly al sees the end of the trail 35 m ahead and decides to speed up to reach it. he accelerates at a constant rate of 0.50 m/s2, while bert continues on at a constant speed. (a) how long does it take al to reach the end of the trail? (b) once he reaches the end of the trail, he immediately turns around and heads back along the trail with a constant speed of 0.85 m/s. how long does it take him to meet up with bert? (c) how far are they from the end of the trail when they meet?

Hydrogen and helium are both members of?

An athlete is holding 24 lb of weights at a height of 6 inches above the stack as shown. to lower the weights, she applies a constant force of 5 lb to the handle. determine the velocity of the weights immediately before they hit the stack.