Arock is thrown straight up into the air. at the
highest point of the rock’s path, the magnitude of
the net force acting on the rock is
(1) less than the magnitude of the rock’s weight,
but greater than zero
(2) greater than the magnitude of the rock’s
weight
(3) the same as the magnitude of the rock’s
weight
(4) zero

Write the equation for momentum, first using symbols for the variables, then using words for the variables.

In which of the following cases is work being done on an object? question 2 options: pulling a trailer up a hill carrying a box down a corridor suspending a heavy weight with a strong chain pushing against a locked door

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)