Problem 15
The coefficient of kinetic friction between a large box and the floor is \(0.21\). A person pushes horizontally on the box with a force of \(160 \mathrm{~N}\) for a distance of \(2.3 \mathrm{~m}\). If the mass of the box is \(72 \mathrm{~kg}\), what is the total work done on the box?
Problem 16
A 13-g goldfinch has a speed of 8.5 m>s. What is its kinetic energy?
Problem 16
A \(13-\mathrm{g}\) goldfinch has a speed of \(8.5 \mathrm{~m} / \mathrm{s}\). What is its kinetic energy?
Problem 17
The kinetic energy of a small boat is \(15,000 \mathrm{~J}\). If the boat's speed is \(5.0 \mathrm{~m} / \mathrm{s}\), what is its mass?
Problem 17
The kinetic energy of a small boat is 15,000 J. If the boat’s speed is 5.0 m>s, what is its mass?
Problem 18
What is the speed of a \(0.15-\mathrm{kg}\) baseball whose kinetic energy is \(77 \mathrm{~J}\) ?
Problem 18
What is the speed of a 0.15-kg baseball whose kinetic energy is 77 J?
Problem 20
At \(t=1.0 \mathrm{~s}\), a \(0.40-\mathrm{kg}\) object is falling with a speed of \(6.0 \mathrm{~m} / \mathrm{s}\). At \(t=2.0 \mathrm{~s}\), it has a kinetic energy of \(25 \mathrm{~J}\). (a) What is the kinetic energy of the object at \(t=1.0 \mathrm{~s}\) ? (b) What is the speed of the object at \(t=2.0 \mathrm{~s}\) ? (c) How much work was done on the object between \(t=1.0 \mathrm{~s}\) and \(t=2.0 \mathrm{~s}\) ?
Problem 20
At t = 1.0 s, a 0.40-kg object is falling with a speed of 6.0 m>s. At t = 2.0 s, it has a kinetic energy of 25 J. (a) What is the kinetic energy of the object at t = 1.0 s? (b) What is the speed of the object at t = 2.0 s? (c) How much work was done on the object between t = 1.0 s and t = 2.0 s?
Problem 21
As an Acapulco cliff diver drops to the water from a height of 46 m, his gravitational potential energy decreases by 25,000 J. What is the diver’s weight in newtons?
