Question

Natalie, Sadie, and Maddie go tobogganing on one of those icy hills; which is so slippery it can be considered to be frictionless. It is real snow, not the fake stuff. They start from an initial speed of 2.3 m/s at the top of the hill. The toboggan has a mass of 3.0 kg and the three students have a combined mass of 250 kg. It is a sunny day and the snow has a temperature of -4℃!

Answer 1

Find their initial combined kinetic energy:

$$E=\frac12mv^2+\frac12Mv^2,\\\space\\ E=\frac12·3·2.3^2+\frac12·250·2.3^2=669.2\text{ J}.$$