Question

net force worksheet

in the example with the penguin sliding across the ice to the left, why was there no arrow for friction on the diagram (since the skate was in contact with the ice and it was moving and there should be friction)?

○ since the surface was ice, the amount of friction is so small that it considered negligible and left off
○ there is no gravity on ice
○ penguins negate all friction by their very nature
○ there is never an arrow for friction

Explanation:

Friction depends on the nature of surfaces. Ice has a very smooth surface, so the frictional force between the penguin (or any object) and ice is extremely small. In physics problems, when a force is very small (negligible), it is often omitted from diagrams for simplicity. Gravity acts everywhere near Earth's surface (including on ice), so option B is wrong. Penguins have no special property to negate friction (option C is incorrect). Friction arrows are drawn when the frictional force is significant (so option D is wrong).

Answer:

A. since the surface was ice, the amount of friction is so small that it considered negligible and left off