Physics

Problem

40\,\text{kg}

student stands on a frictionless skateboard next to a rigid wall. She pushes the wall horizontally with an average force of

20\,\text{N}

for

0.4\,\text{s}

and then stops pushing. Neglect all other forces. What is her speed immediately after the push? a)

0.20\,\text{m/s}

towards the wall b)

0.40\,\text{m/s}

away from the wall c)

0.20\,\text{m/s}

away from the wall d)

0.05\,\text{m/s}

away from the wall