Which of the following is an example in which you are traveling at constant speed but not at constant velocity? a) rolling freely down a hill in a cart, traveling in a straight line b) driving backward at exactly 50 km/hr c) driving around in a circle at exactly 100 km/hr d) jumping up and down, with a period of exactly 60 hops per minute e) none of the above

Speed is defined as rate of change in position or we can say it is ratio of total distance moved in total interval of times

While in order to find the velocity we know that it is ratio of total displacement and total time

so here main difference is that speed is scalar quantity and we do not require any direction in speed while in velocity we require direction as well as magnitude

Here we need to select a case where speed is constant while velocity is not constant.

It is only possible when direction is continuously changing but magnitude remains the same

so here correct answer will be

C) driving around in a circle at exactly 100 km/hr

i don't know that i agree with that but what's the question ?

this could be newton#'s law of cooling. the cooling curve is exponential