Respuesta :
Answer:
0.0241 m
Explanation:
mass of the hockey player m1 = 90 kg
mass of puck m2 = 0.150 kg
puck velocity v1= 45 m/s
distance traveled by puck to reach the goal =15.0 m.
now accoding to momentum conservation law
90×45+0.15×v2 = 0 [ since, If both are initially at rest and if the ice is frictionless,]
therefore, v2= -0.0725 m/s.
Now time taken by the puck to reach the goal
t= 15/45 = 1/3 sec.
therefore, how far does the player recoil in the time
=0.0725×1/3= 0.0241 m.
the distance travelled by the player( recoil ) in the time the puck reach the goal is 0.025m.
Given the data in the question
- Mass of the player; [tex]m_1 = 90.0kg[/tex]
- Mass of puck; [tex]m = 0.150kg[/tex]
Since they were both at rest initially
- Initial velocity of player; [tex]u_1 = 0[/tex]
- Initial velocity of puck; [tex]u = 0[/tex]
- Velocity of player after the hit; [tex]v_1 = \ ?[/tex]
- Velocity of puck after the hit; [tex]v = 45.0m/s[/tex]
- Distance to the goal; [tex]s = 15.0m[/tex]
Using conservation of liner momentum:
[tex]mu + m_1u_1 = mv+ m_1v_1[/tex]
Now, Since they were both at rest initially
[tex]0 = mv+ m_1v_1[/tex]
We substitute in our values to find the velocity of the player after the hit ( recoil velocity )
[tex]0 =[ 0.150kg * 45.0m/s ] + [ 90.0kg * v_1 ]\\\\0 = 6.75kg.m/s + [ 90.0kg * v_1 ]\\\\90.0kg * v_1 = -6.75kg.m/s \\\\v_1 = -\frac{6.75kg.m/s}{90.0kg} \\\\v_1 =- 0.075m/s[/tex]
{ The negative sign shows that the velocity of both the player and the puck are in opposite direction }
Hence, recoil velocity of the player is 0.075m/s
Now, we determine the time taken for the puck to trach the goal using the relation between distance, velocity and time .
Time = Distance / Velocity
We substitute our values into the expression
[tex]t = \frac{s}{v} \\\\t = \frac{15.0m}{45m/s} \\\\t = 0.3333s[/tex]
Hence, the time taken for the puck to reach the goal is 0.3333 seconds.
Next, we determine the distance travelled by the player( recoil ) in the time the puck reach the goal using the relation between distance, velocity and time .
Time = Distance / Velocity
We substitute in our values
[tex]t = \frac{s}{v}\\\\0.3333s = \frac{s}{0.075m/s} \\\\s = 0.3333s * 0.075m/s\\\\s = 0.025m[/tex]
Therefore, the distance travelled by the player( recoil ) in the time the puck reach the goal is 0.025m.
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