Problem 10
Is it possible to do work on an object that remains at rest? Explain.
Problem 11
Give two examples of (a) positive work done by a frictional force (if possible) and (b) negative work done by a frictional force.
Problem 11
Give Examples Give two examples of (a) positive work done by a frictional force (if possible) and (b) negative work done by a frictional force.
Problem 12
Calculate A child in a tree house uses a rope attached to a basket to lift a 22-N dog upward through a distance of 4.7 m into the house. How much work does the child do in lifting the dog?
Problem 12
A child in a tree house uses a rope attached to a basket to lift a \(22-\mathrm{N}\) dog upward through a distance of \(4.7 \mathrm{~m}\) into the house. How much work does the child do in lifting the dog?
Problem 13
Calculate To move a suitcase up to the check-in stand at an airport, a student pushes with a horizontal force through a distance of 0.95 m. If the work done by the student is 32 J, what is the magnitude of the force he exerts?
Problem 13
To move a suitcase up to the check-in stand at an airport, a student pushes with a horizontal force through a distance of \(0.95 \mathrm{~m}\). If the work done by the student is \(32 \mathrm{~J}\), what is the magnitude of the force he exerts?
Problem 14
Calculate A farmhand pushes a bale of hay 3.9 m across the floor of a barn. She exerts a force of 88 N at an angle of 25 below the horizontal. How much work has she done?
Problem 14
A farmhand pushes a bale of hay \(3.9 \mathrm{~m}\) across the floor of a barn. She exerts a force of \(88 \mathrm{~N}\) at an angle of \(25^{\circ}\) below the horizontal. How much work has she done?
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?
