A hovercraft of mass 83.0 kg can move on a horizontal surface, the x-y plane. A single unbalanced force acts on the hovercraft, but the size of the force is unknown. The hovercraft initially has a velocity of 4.0 m/s in the positive x direction and some time later has a velocity of 7.0 m/s in the positive y direction. How much work is done on the hovercraft by the force during this time?

1369.5 J

Explanation:

According to the work-energy theorem, the work done on an object is equal to the change in kinetic energy of the object itself.

Therefore, we can write:

where:

W is the work done on the hovercraft

m = 83.0 kg is the mass of the hovercraft

u = 4.0 m/s is the initial velocity (in the positive x-direction)

v = 7.0 m/s is the final velocity (in the positive y-direction)

Here the direction of motion of the hovercraft has changed; however, we can ignore this fact, since work is a scalar so the direction of the velocity does not matter.

Therefore, the work done by the force is:

sleep paralysis is a parasomnia, events associated with sleep.

sleep paralysis happens when you are in the middle of waking up or falling asleep. it is the feeling of being conscious but unable to move. it definitely involves hallucinations.

i had a friend that had sleep paralysis and he told me a story one time where he was laying in bed and he couldn't move his body no matter how hard he tried and there was someone standing in the corner of his room coming towards him. he couldn't move and you can't "wake up" because you are already conscious. sometimes sleep paralysis can be triggered by frequent waking up during the night based off of multiple trips to the bathroom, or if you had ever been abused, sleep paralysis can start happening from things like that.