Challenging Physics Skateboard question involving Energy. 10 points for...

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Flasher

New member
...correct answer!!? You are helping your friend prepare for her next skate board exhibition.
For her program, she plans to take a running start and then jump onto her heavy duty 10 kg stationary skateboard. She and the skateboard will glide in a straight line along a short, level section of track, then up a sloped concrete wall. She wants to reach a height of at least a metre above where she started before she turns to come back down the slope. She has measured her maximum running speed to safely jump on the skateboard at 4.3 metres per second. She knows you have taken physics, so she wants you to determine if she can carry out her program as planned. She tells you that she weighs 47 kg. Her skateboard seems to roll a long way by itself when pushed, so you feel that it is probably safe to neglect friction in your calculations.


How high will she go above where she started?
 
as max height for projectile is

h= v^2sin^2Q /2g where Q= angle of jump
max height when q= 90 degree
substituting Q=90

h= 4.3*4.3/2/9.8
h=0.94m
so even she jumps vertically up she cant attain a height of 1 m with this speed
 
Here kinetic energy at the base is converted to potential energy at her maximum height up the wall.

Kinetic Energy at the base = 0.5*m*v²; m = 10+47 = 57 kg, v = 4.3 m/s
KE = 527 J

Potential energy at height h = m*g*h = 57*9.8*1 = 559 J

There is not enough kinetic energy for her to reach a height of 1 m

To determine how high she will go, equate the initial KE with PE at h:

m*g*h = 0.5*m*v²

h = 0.5*v²/g = 0.94 m
 
her mass 47 kg
mass of skateboard is 10kg
so total mass is 57kg
velocity is 4.3m/s
so momentum is=mass*vel=57*4.3=245.3kgm/s
now i dont know how to calc if it is possible for her to climb it
 
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