A hawk, weighing 0.4 kg, is lifted by an air stream to a height of 70 m. Determine the work of force that lifted the bird.

Answer: 280 J.
Explanation of the solution: to solve this problem, you must use the formula:
A = F * l, where F is the force of gravity, l is the length of the traveled path (in our case, this is the height), A is the work of force.
In addition, F = m * g, where m is body mass, g is gravitational acceleration, g = 10 N / kg.
Substituting the known values from the condition into the formula, we get the following:
A = F * l = m * g * l = 0.4 * 10 * 70 = 280 J.