1. A knife thrower throws a knife toward a 300-g target that is sliding in her d
ID: 1285964 • Letter: 1
Question
1. A knife thrower throws a knife toward a 300-g target that is sliding in her direction at a speed of 2.25 m/s on a horizontal frictionless surface. She throws a 22.5-g knife at the target with a speed of 39.0 m/s. The target is stopped by the impact and the knife passes through the target. Determine the speed of the knife after passing through the target.
____ m/s
2. A cannon elevated at some angle ? (unknown) fires a shell with some initial speed v0 (unknown) that has a range R when fired over level ground (see Figure (a)). During a test fire, a shell explodes at the top of the trajectory into two unequal mass fragments. The shell explodes in such a manner that neither fragment experiences a change in momentum in the y direction. However, 30% of the shell (m2) continues onward and the other fragment (m1) falls straight down. Determine the distance D (in terms of R) that the forward moving fragment lands from the cannon (see Figure (b)).
D =
I GIVE POINTS BACK IMMEDIATELY TO PERSON WHO ANSWERS IT CORRECTLY!
CHECK OUT MY OTHER EASY QUESTIONS:
http://www.chegg.com/homework-help/questions-and-answers/bullet-mass-m-speed-v-fired-hits-passes-completely-pendulum-bob-mass-m-end-stiff-rod-negli-q6042083
http://www.chegg.com/homework-help/questions-and-answers/three-masses-b-c-momentum-moving-across-horizontal-frictionless-surface-masses-respectivel-q6042081
http://www.chegg.com/homework-help/questions-and-answers/man-holding-rock-sits-sled-sliding-across-frozen-lake-negligible-friction-speed-0490-m-s-t-q6042079
Explanation / Answer
1)
Knife KE = 1/2 mv^2
KE = 0.5 * 0.0225 kg * (39 m/s)^2 = 17.11 J
target KE = 0.5 * 0.3 kg * ( 2.25 m/s)^2 = 0.759 J
Energy of the arrow stopped the energy of the target:
17.11 J - 0.759 J = 16.35 J of energy left over for arrow after passing thru target
1/2 mv^2 = 16.35 J
0.5 * v^2 = 16.35 /0.0225
v^2 = 1453.33 m^2/s^2
v = 38.12 m/s
2)
range of object projected by cannon at an angle ?
R = (V^2/g) * sin(2?)
V is initial velocity in m/s
g is the acceleration of gravity 9.81 m/s
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.