Calculating Net Acceleration of a Toy Cricket with a Spring | Physics Problem

[jehan4141]

I've been trying to figure this problem out for a few hours now. Please, if you have helpful hints, help me out!

You can see the problem here on page 7, the problem about the toy cricket: http://www.physics.princeton.edu/~mcdonald/examples/ph101_2006/learning_guide_ph101_2006.pdf
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A toy cricket is stuck to the floor with a suction cup which after a few moments releases to allow a spring to propel the cricket upward. The expanding spring accelerates the cricket over a distance of 0.01 m to point A, after which the toy travels freely to a maximum height of 1.00 m above the ground (point B).

What is the net acceleration during the time the spring expands? Assume uniform acceleration.

The answer is 970 m/s^2.

I just do not know where to start. I assume we use x = (1/2)(acceleration)(t^2) but don't know enough of the variables to plug and chug.

 

[cupid.callin]

you have solved 1,2 parts
so now you have speed when spring is completely expanded.

for the accelerating motion you have final vel., initial vel. , height
which Newton eqn can be used to find acc.?

 

[jehan4141]

Still confused...

Aren't they asking for the acceleration when the spring remains on the ground? Once the spring gets to point A, it jumps up in the air. Am I picturing this incorrectly?

For the question, I thought they wanted the acceleration for when it travels 0.01 meters and that the spring is fully expanded by the time it jumps off the ground at point A.

 

[gdbb]

You have to work this problem in a couple steps. First, find out the velocity at which the cricket has to travel in order to go from 0.01 m to 1.00 m when only gravity is exerting a force on it. I'll let you see if you can figure out the rest from there. :)

 

[jehan4141]

omg you guys are geniuses...I just got it. physics is so difficult for me! thank u so much u guys

 

[cupid.callin]

no, the spring is expanding from A to C ... and then goes, under gravity effect, from C to B and then back.

for A-C motion, it experiences gravitational force and also a spring force (which is not constant but here its given for the sake of simplicity).

and then are asking acc. in A-C motion
C-B motion will have acc. g

 

[gdbb]

You're welcome! Practice definitely makes perfect in physics.

 

[cupid.callin]

omg you guys are geniuses...I just got it. physics is so difficult for me! thank u so much u guys

 

[jehan4141]

i am having to re-take physics next year..so I am trying to improve during the summer! :) i hope practice DOES make perfect ))))

 

[jtbell]

I'd like to remind people of our rule that we give only hints, not complete solutions. (just in case you're wondering what happened to the most recent posts in this thread.)