Question

1, Ebo through a ball into the air. its velocity at the start is 18m/s at an angle of 37° to the ground.
a, Express the initial velicity in component vector form
b, Work out the velocity of the ball as it lands. give answer in component vector form.
c, Work out the range of the ball.
d, What assumptions have been made about the frame reference?

Answer 1

a.
Vx = 18 cos 37 forever
Vy = 18 sin 37 at start
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b.
assuming it started at ground level the x velocity will be the same but the y velocity will be the same magnitude but down not up
Vx = 18 cos 37 forever
Vy = -18 sin 37 at landing

c.
how long until it lands?
h = Hi + Vi t - 4.9 t^2
Hi = h = 0 at ground
Vi = 18 sin 37
so at the end
0 = 0 + 18 sin 37 * t - 4.9 t^2
(4.9 t - 18 sin 37 ) t = 0
so at the ground = t = 0 and at t = (18/4.9)sin 37
so
x = Vx t = (18 cos 37) (18 sin 37 ) / 4.9

d. well as I said I assumed the ball started at the ground level but the kid probably had finite height. It is an inertial frame, not really earth with its Coriolis effect etc.

Answer 2

A brass rod 2m long at a certain temperature.what is it’s length after a temperature rise of 100k if the expansivity of brass is 18x10-6k-1

Answer 3

18. 9

Answer 4

Biniyam Tefera