The distance between two cities is 144km; it takes me 3 hours to travel between these cities. What average speed did I travel at?

Idon’t quite understand this problem

Ascientific blank must be testable and capable of being proven false?

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.)