Physics

Problem

A toy car of mass

2\,\text{kg}

rolls at

3\,\text{m/s}

. It picks up an extra block so that its mass becomes

3\,\text{kg}

and its speed drops to

2\,\text{m/s}

. The car is then pushed and its speed increases to

6\,\text{m/s}

while the mass remains

3\,\text{kg}

. What is the ratio of the car’s final kinetic energy to its initial kinetic energy? a)

4

6

9

3