Figure P3.58 3.58 Kicking an Extra Point. In Canadian football, after a touchdown the team has the opportunity to earn one more point by kicking the ball over the bar between the goal posts. The bar is 10.0 ft above the ground, and the ball is kicked from ground level, 36.0 ft horizontally from the bar ( Fig. P3.58 ). Football regulations are stated in English units, but convert them to SI units for this problem, (a) There is a minimum angle above the ground such that if the ball is launched below this angle, it can never clear the bar, no matter how fast it is kicked. What is this angle? (b) If the ball is kicked at 45.0° above the horizontal, what must its initial speed be if it is just to clear the bar? Express your answer in m/s and in km/h.
Figure P3.58 3.58 Kicking an Extra Point. In Canadian football, after a touchdown the team has the opportunity to earn one more point by kicking the ball over the bar between the goal posts. The bar is 10.0 ft above the ground, and the ball is kicked from ground level, 36.0 ft horizontally from the bar ( Fig. P3.58 ). Football regulations are stated in English units, but convert them to SI units for this problem, (a) There is a minimum angle above the ground such that if the ball is launched below this angle, it can never clear the bar, no matter how fast it is kicked. What is this angle? (b) If the ball is kicked at 45.0° above the horizontal, what must its initial speed be if it is just to clear the bar? Express your answer in m/s and in km/h.
3.58 Kicking an Extra Point. In Canadian football, after a touchdown the team has the opportunity to earn one more point by kicking the ball over the bar between the goal posts. The bar is 10.0 ft above the ground, and the ball is kicked from ground level, 36.0 ft horizontally from the bar (Fig. P3.58). Football regulations are stated in English units, but convert them to SI units for this problem, (a) There is a minimum angle above the ground such that if the ball is launched below this angle, it can never clear the bar, no matter how fast it is kicked. What is this angle? (b) If the ball is kicked at 45.0° above the horizontal, what must its initial speed be if it is just to clear the bar? Express your answer in m/s and in km/h.
Use the component method to add the vectors A
and B shown in Figure P3.9. Both vectors have mag-
nitudes of 3.00 m and vector A makes an angle of
0 = 30.0° with the x axis. Express the resultant Á + B in
unit-vector notation.
A force F, of magnitude 6.00
units acts on an object at the ori-
gin in a direction 0
the positive x axis (Fig. P3.7). A
second force F, of magnitude
5.00 units acts on the object
in the direction of the positive
y axis. Find graphically the magni-
tude and direction of the resultant
force F, + F,.
30.0° above
Figure P3.7
The displacement vectors A and B shown in Figure P3.9 both have magnitudes of 3.00 m, The
direction of vector A is 0 = 30.0°. Find graphically
9.
(a) +B,
Answer +
(b) A - B,
Answer +
(c) B - 7, and
Answer +
(d) A- 2B. (Report all angles counterclockwise from the positive = axis.)
Figure P3.9
Problems 9 and 25.
Chapter 3 Solutions
University Physics with Modern Physics (14th Edition)
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