Physics Homework Help?

Lizzy

Vector A is 3.00 units in length and points along the positive x axis. Vector B is 3.00 units in length and points along the negative y axis. Use graphical methods to find the magnitude and direction of the vectors below.
(a) A + B
(I already got units its 4.24)
___degrees (relative to the +x axis)
(b) A - B
(already got units its 4.24)
___ degrees (relative to the +x axis)



A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 20.0 m/s. The cliff is h = 54.0 m above a flat horizontal beach
How long after being released does the stone strike the beach below the cliff?
____s
With what speed and angle of impact does it land?
____m/s (speed)
____degrees (below the horizontal)



Tom the cat is chasing Jerry the mouse across a table surface 1.3 m off the floor. Jerry steps out of the way at the last second, and Tom slides off the edge of the table at a speed of 5.1 m/s. Where will Tom strike the floor?
____m from the table
What velocity components will he have just before he hits? (Use a coordinate system in which up is positive.)
____m/s (x direction)
____m/s (y direction)



A science student is riding on a flatcar of a train traveling along a straight horizontal track at a constant speed of 9.0 m/s. The student throws a ball along a path that she judges to make an initial angle of 50.0° with the horizontal and to be in line with the track. The student's professor, who is standing on the ground nearby, observes the ball to rise vertically. How high does the ball rise?
____m



A daredevil decides to jump a canyon. It's walls are equally high and 12 m apart. He takes off by driving a motorcycle up a short ramp sloped at an angle of 14°. What minimum speed must he have in order to clear the canyon?
____m/s

Answer
vector A: first one is -45º = 315º w/r/t +x
second one is 45º

science student: horiz Vh = Vcos50 = 9m/s, so V = 14 m/s
max. height = (V·sinÎ)² / (2g) = (14m/s * sin50)² / 19.6m/s² = 5.9 m

daredevil: range = (V²sin(2Î))/g
12 m = V² * sin28º / 9.8m/s²
V = 16 m/s

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