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1) A boulder flies through the air at 10.3 m/s with kinetic energy 292J

 

With this info how do i find

 

A) The mass of the boulder?

 

 What's the boulder's kinetic energy if its speed doubles?

 

C) What's the boulder's kinetic energy if its speed is halved?

 

2) A baseball with mass 0.145kg is pitched at 37.6 m/s. Upon reaching home plate, 16.9m away, its speed is 36.1m/s.

 

I have no idea how to find...

 

A) If the decrease is due entirely to drag, find the work done by the drag force.

 

 Find the magnitude of the (assumed constant) drag force

 

3) How far must you compress a spring with k=668N/m in order to store 496J of energy

 

Where do I start?

 

4) The total mechanical energy of an object moving at 31.3m/s is 525J, and its potential energy is 174J

 

A) What's its mass?

 

I have no idea where to start and what formula to plug numbers. I can not find any of this in my notes......Help

 

 

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[a sudden stop, a car's seatbelt provides the force that stops the passenger.]

Thanks Fizz you are the man.  Im gonna hang this up until tomorrow

[a sudden stop, a car's seatbelt provides the force that stops the passenger.]

what is this called and where can i find videos to help me out

[a sudden stop, a car's seatbelt provides the force that stops the passenger.]

the problem reads 

 

a sudden stop, a car's seatbelt provides the force that stops the passenger.

 

For a 80kg passenger,

what's the seatbelt force if a car goes from highway speed of 90.0km/h to rest in 5.1s ?

[finding the net force of beam and beam acceleration]

A crane lifts a 225kg steel beam, applying a 2430N vertical force

 

Find the net force on the beam

 

Find the beam's acceleration