Two soccer players on a breakaway start from midfield and run straight down the field with a separation of d = 5 m and with the same velocity v = 7 m/s . The last defensive player of the other team approaches the player who has the ball, so that person decides to pass the ball with velocity u = 1 0 m/s to their teammate. At what angle in degrees with respect to their trajectory should they pass the ball so it reaches their teammate?
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u said with respect to the trajectory....so shouldn't it be parallel to the 5 m distance between them making it sin inverse(7/10)??????
Let the ball reach the other player P in time t . In this time, P would travel the distance 7 t ; the ball would travel 5 m perpendicular to P ’s trajectory and 7 t along P ’s trajectory. Therefore, the distance l that the ball travels can be expressed in t by Pythagoras from a right triangle to be 2 5 + 4 9 t 2 .
Since we know the velocity u of the ball, we can determine t from u = t l as 1 0 = t 2 5 + 4 9 t 2 . Solving this for positive t values gives t = 5 1 2 5 .
Now we can find the angle from the same right triangle we expressed l from, since tan ( 2 π − α ) = 5 7 t = 5 7 ⋅ 5 1 2 5 = 0 . 9 8 0 2 . Hence, α = 2 π − arctan 0 . 9 8 0 2 = 4 5 . 5 7 ∘
This is a nice solution, although it is a bit unnecessarily complicated. See Kyle's solution (or mine).
Since the ball and the teamate both move at a constant rate, you know that the distance each moves will be the same ratio of 7/10. The angle you want the complement of sin(7/10), which is approximately 45.57.
45.573
The ball and the player both have got to reach a certain point after a certain time t . Let us call this point O and the points of where the player with the ball and his teammate are with P 1 and P 2 accordingly.
Now, let us form a triangle with sides P 1 P 2 = 5 , P 1 O = c and P 2 O = b ( P 1 P 2 is actually the distance between the two players, which we know). This triangle is also a right one, with the right angle being ∠ P 1 P 2 O .
Now, we know for a fact that because v = t s , where v is the velocity, s is the length traveled and t is the time, the two missing sides of the triangle can be expressed as
b = 7 t and c = 1 0 t
The angle we are actually looking for is ∠ P 2 O P 1 , which we will call ∠ α for better illustrative purposes. From the given triangle, we know that
cos α = c b ⇒ cos α = 1 0 7
From this point on, we simply find arccos 1 0 7 , which is 4 5 , 5 6 8 .
Thus, the answer is 4 5 , 5 7 .
Let * \( x \) * be the displacement of the ball respect the trajectory of the players. Let α be the angle we want to know. We know the ball's speed is 10 m/s. Part of that speed must go move 5 m perpendicularly to their trajectory. That will be \(10 \times \sin \alpha \). By the other hand, the speed parallel to their trajectory will be the same speed as the players, 7 m/s. So \(7 = \10 \times \cos \alpha \). We can solve the angle now. Note that \(10 \times \sin \alpha \) is not necessary. Finally, we have \(\frac{7}{10} = \cos \alpha \), so \(alpha = 45.573 \)
consider two players. velocity of both the players are 7m/s. velocity of ball when he passes the ball = 10 m/s. now applying trigonometry ; sin (x) = 7/10. which gives x = 44.427004. bt according to ques wee should subtract our ans from 90 because we want angle with respect to their trajectory. therefore ans is 90- x i.e 45.572996
Let t be the amount of time it takes for the soccer ball to transfer between the two players. In that time, the ball travels 1 0 t m and the receiving player travels 7 t m . The angle θ between the trajectory of the defender and the trajectory of the ball therefore has cosine 7 / 1 0 (draw the diagram to see this.) Thus, we have θ = arccos ( 7 / 1 0 ) ≈ 4 5 . 6 ∘ .
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Let t be the time it takes for the pass to occur. In this time, the receiver runs a distance 7 t , in S.I. units. The component of the velocity of the ball that is parallel to the trajectories of the runners is 1 0 cos θ , where θ is the desired angle.
Now, the two horizontal distances run the ball and the receiver must be the same, so: 1 0 t cos θ = 7 t ⟹ cos θ = 1 0 7 . Thus, taking the arccosine, we have θ = 4 5 . 5 7 ∘ .