When we carry an object across the room, without lifting it or setting it down, we do no physical work on it. true false
More work is needed to carry a heavy suitcase slowly up a flight of stairs than to carry the suitcase quickly up the same flight of stairs. true false
The amount of potential energy possessed by an elevated object is equal to the distance it is lifted, the force needed to lift it, the work done in lifting it, or the value of the acceleration of gravity.
Ralph asked me a question about today's reading assignment. According to the reading assignment, a car coasting from rest down two hills, one steeper than the other, would arrive at the bottom of each hill with the same speed, as long as the two hills have the same vertical height. (Of course, this is true only if we neglect friction and air resistance.) Ralph wondered how this could be possible, since the acceleration of the car down the steep hill is much greater than down the other hill. The distance down the other hill is greater, so, although the car has less acceleration, it has more time to reach its final speed.