Homework Help: physics i really need help :(

Posted by juanita on Saturday, November 24, 2012 at 8:19pm.

A projectile is fired with an initial speed of 61.3m/s at an angle of 31.5° above the horizontal on a long flat firing range.
a)Determine the maximum height reached by the projectile.
b)Determine the total time in the air.
c)Determine the total horizontal distance covered (that is, the range).
d)Determine the speed of the projectile 1.44s after firing.
e)Determine the direction of the projectile 1.44s after firing.

physics i really need help :( - Damon, Saturday, November 24, 2012 at 8:41pm
a
vertical problem
vi = 61.3 sin 31.5 = 32 m/s up
when at top (v = 0) ?
o = 32 - 9.81 t
t = 3.26 seconds to max ht
how high?
h = Vi t - (1/2)(9.81)t^2
h = 32 (3.26) - 4.9(10.7)
= 51.9 m high
-------------
easier way by the way:
average speed up = 32/2 = 16m/s for 3.26 seconds --> 52 m
--------------------------
b
time in air = twice the time up = 3.26*2 = 6.52 seconds
c
horizontal problem
constant horizontal speed = 61.3 cos 31.5 = 52.3 m/s
time is still 6.52 s
range = 52.3 * 6.52 = 341 meters

d
vertical problem
v = 32 - 9.81 (1.44)
= 17.9 m/s
horizontal speed is always 52.3
s = sqrt(17.9^2+2.3)^2

e
tan angle up from hor = 17.9/52.3
= 18.9 degrees up from horizontal

Answer this Question

Related Questions

PHYSICS! - A projectile is fired with an initial speed of 32.5 m/s at an angle ...
PHYSICS! - A projectile is fired with an initial speed of 32.5 m/s at an angle ...
Physics - a projectile is fired with an initial speed of 53 m/s. Find the angle ...
Physics - a) A cannonball is fired horizontally from the top of a cliff. The ...
physics - 1. A certain projectile is launched with an initial speed v0. At its ...
College Physics - 1. A certain projectile is launched with an initial speed v0...
Physics - A projectile is fired from ground level with a speed of 40 m/s at an ...
Physics - A projectile is fired with an initial speed v0 at t = 0. The angle ...
physics HELP - A projectile is fired with an initial speed of 1000 m/s at an ...
physics - A projectile is fired with an initial speed of 26.0 m/s at an angle of...

For Further Reading

First Name:
School Subject:
Answer: