17.3: Examples
A bartender slides a bottle down his bar to a customer. Unfortunately, he pushes it too hard and the bottle flies off the end of the bar!
- The force of friction between the bar and the bottle is 0.150 N, and the bottle has a mass of 0.520 kg. What is the acceleration of the bottle as it travels down the bar?
- If it started with a speed of 2.97 m/s, what is the speed of the bottle as it leaves the bar, 2.80 m away from where the bartender pushed it?
- Black Hat from the webcomic XKCD is standing nearby, a distance 1.25 m from the end of the bar (which is 1.15 m tall). Does the bottle hit him after it slides off the end of the bar?
Consider two blocks which are in contact with each other on a horizontal frictionless surface. The masses of the blocks are 5 kg and 10 kg. The 5 kg block is being pushed with an unknown force \(F_p\), which then pushes on the 10 kg block, making them both accelerate to the right at 2.00 m/s\(^2\).
- How big is the force pushing on the 10 kg block from the 5 kg block?
- What is the magnitude of the pushing force \(F_p\)?
Consider three blocks which are in contact with each other on a horizontal frictionless surface. From left to right, the masses of the blocks are 5 kg, 10 kg, and 25 kg. The leftmost block is being pushed to the right with an unknown force \(F_p\), and the blocks are accelerating to the right at 2.00 m/s\(^2\).
- What is the magnitude and direction of the forces the blocks are exerting on each other?
- What is the magnitude of the pushing force \(F_p\)?
A 40.0 kg crate is sitting on top of a 60.0 kg crate on the floor of an elevator. The elevator floor is exerting an upwards force of 1050 N to the 60.0 kg crate.
- Determine the magnitude and direction of the acceleration of the crates in the elevator.
- Determine the magnitude and direction of the contact force that the 40.0 kg crate exerts on the 60.0 kg crate.
- Determine the magnitude and direction of the contact force that the 60.0 kg crate exerts on the 40.0 kg crate.