An airplane was moving 50 mys to the north relative to the air at landing. The wind was blowing 5 m/s toward the south relative to the ground. What was the speed of the airplane relative to the ground at the time of landing?
10 m/s
45 m/s
55 m/s
250 m/s

Aplayground slide is 8.80 ft long and makes an angle of 25.0° with the horizontal. a 63.0-kg child, initially at the top, slides all the way down to the bottom of the slide. (a) choosing the bottom of the slide as the reference configuration, what is the system's potential energy when the child is at the top and at the bottom of the slide? what is the change in potential energy as the child slides from the top to the bottom of the slide? (include the sign of the value in your answer.)