Tamara exerts a force downward on a chair by sitting on it. Which of the following statements best explains why the chair does not move downward?
A The chair exerts an upward force that is greater than the force exerted by Tamara
B
The floor exerts an upward force that is greater than the force exerted by Tamara
The chair exerts an upward force that balances the downward force exerted by Tamara
D
The floor exerts an upward force on the chair that balances the downward force exerted by Tamara

You carry a 7.0-kg bag of groceries 1.2 m above the ground at constant speed across a 2.7m room. how much work do you do on the bag in the process? (a) 157j (b) 0.00j (c) 185j (d) 82j

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value