A wind with speed 45 m/s blows across a roof 20 m long and 12 m wide. The pressure inside the room is 1 atm. What is the net force on this roof due to the pressure difference inside and outside the roof? (The density of air is equal to 1.3 kg/m3.) A) 2.4 x107 N
B) 6.3 x 105 N
C) 3.2 x 105 N
D) 7.0 x 103 N
E) 3.2 x 108 N

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.)