Kinematics in two Dimensions -- Projectile launched from the edge of a cliff

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  • #1
Har2803
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Homework Statement:
A bomb of mass 15.0 kg with an initial velocity of 350 m/s and horizontal velocity of 250 m/s is
projected from the edge of a cliff of a height 500 m. The kinetic energy just before it hits the target
is 500 kJ.
(a) Determine the initial kinetic energy of the bomb.
[2 Marks]
(b) Show the change of kinetic energy of the bomb.
[2 Mark]
(c) Find the value of the initial angle.
[2 Marks]
(d) Calculate the height of the target from the ground.
[4 Marks]
(e) Determine the kinetic energy and velocity at the height of 2.50 × 103 m from the
ground? [5 Marks]
Relevant Equations:
v^2=u^2+2as
For parts (d) and (e) I can't figure out the required steps to get the height due to the fact that I don't have the acceleration. I may have done a miscalculation for the former questions as well. I also feel (e) requires the value of a. Hope someone can help me out. Been going at this question for 2 days now.
 

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  • #2
Delta2
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Isn't the movement of the bomb inside the gravitational field of earth?
Isn't the gravitational acceleration of earth, g, given by the problem?

If g is not given by the problem data, then we should be able to find it from other given data, but i am afraid the given data is not enough to find g.
 
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  • #3
Har2803
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Isn't the movement of the bomb inside the gravitational field of earth?
Isn't the gravitational acceleration of earth, g, given by the problem?

If g is not given by the problem data, then we should be able to find it from other given data, but i am afraid the given data is not enough to find g.
That is what I thought as well initially. If i use 9.81 as the value of a in a kinematic eq, I still can't find the height of the target from the ground. I just end up with a value that proves the target is not lifted off the ground at all
 
  • #4
Delta2
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Hmmm you got to show us your workings, but let me ask this do you get a negative value for the height of the target?
 
  • #5
haruspex
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initial velocity of 350 m/s and horizontal velocity of 250 m/s
Something missing? Should that be initial vertical velocity of 350 m/s (up or down?) or perhaps initial speed?
 

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