Two kinematics problems need checking and help

sens · Sep 25, 2016

Homework Statement

Typed homework problem about mountain rescue officers firing a gun at a distant slope: muzzle velocity 253 m/s, horizontal distance x = 1,049 m, vertical distance y = 401 m, with parts a) lowest angle to the horizontal and b) highest angle giving a direct hit.

The Attempt at a Solution

Handwritten kinematics derivation on lined paper: v_i = 253, x_f = 1049, y_f = 401; v_xi = v_i cos θ = 253 cos θ; v_yi = v_i sin θ = 253 sin θ; then x_f = x_i + v_xi t gives t = 1049 / (253 cos θ); then y_f = y_i + v_yi t − 4.9 t² with substitution for t.

The above is my attempt to solve question a), is this right approach? Now all i need to do is solve for theta? Or am i completely off track?

Also, i have no idea how to approach question b). some insight would be helpful... Thanks!

TSny · Sep 25, 2016

Yes, you have the correct approach. Yes, now solve for θ.

Solving (a) will help you see how to answer (b).

sens · Sep 25, 2016

thanks, i figured both of them out :)

The Buttered Cat · Sep 25, 2016

Looks like you're on the right track. Google trigonometric identities to figure out how to solve the quadratic. You'll get two angles as a solution.

Two kinematics problems need checking and help

Homework Statement

The Attempt at a Solution

Discussion

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