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

Har2803
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.

Delta2

## Answers and Replies

Homework Helper
Gold Member
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.

Last edited:
Har2803
Har2803
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

Delta2
Homework Helper
Gold Member
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?