Olaf is standing on a sheet of ice that covers the football stadium parking lot in Buffalo, New York; there is negligible friction between his feet and the ice. A friend throws Olaf a ball of mass 0.400 kg that is traveling horizontally at 10.9 m/s . Olaf's mass is 70.2 kg. (a) If Olaf catches the ball, with what speed vf do Olaf and the ball move afterward? Express your answer numerically in meters per second. (b) If the ball hits Olaf and bounces off his chest horizontally at 8.10 m/s in the opposite direction, what is his speed vf after the collision? Express your answer numerically in meters per second.

Respuesta :

Explanation:

Momentum is conserved.

a) In the first scenario, Olaf and the ball have the same final velocity.

mu = (M + m) v

(0.400 kg) (10.9 m/s) = (70.2 kg + 0.400 kg) v

v = 0.0618 m/s

b) In the second scenario, the ball has a final velocity of 8.10 m/s in the opposite direction.

mu = mv + MV

(0.400 kg) (10.9 m/s) = (0.400 kg) (-8.10 m/s) + (70.2 kg) v

v = 0.108 m/s

a) After Olaf catches the ball, Olaf and the ball will move at a speed of 0.062 m/s.

b) The speed of Olaf after the ball bounces off his chest is 0.11 m/s.    

a) We can find the speed of Olaf and the ball by conservation of linear momentum.

[tex] p_{i} = p_{f} [/tex]

[tex] m_{o}v_{i_{o}} + m_{b}v_{i_{b}} = m_{o}v_{f_{o}} + m_{b}v_{f_{b}} [/tex]

Where:

[tex] m_{o}[/tex]: is the mass of Olaf = 70.2 kg

[tex] m_{b}[/tex]: is the mass of the ball = 0.400 kg

[tex] v_{i_{o}}[/tex]: is the intial speed of Olaf = 0 (he is at rest)

[tex]v_{i_{b}}[/tex]: is the initial speed of the ball = 10.9 m/s

[tex] v_{f_{o}}[/tex] and [tex]v_{f_{b}} [/tex]: are the final speed of Olaf and the final speed of the ball, respetively.

Since Olaf catches the ball, we have that [tex] v_{f_{o}} = v_{f_{b}} = v [/tex], so:

[tex] m_{o}v_{i_{o}} + m_{b}v_{i_{b}} = v(m_{o} + m_{b}) [/tex]

We will take the direction of motion of the ball to the right side, and this will be the positive x-direction.  

By solving for "v" we have:

[tex] v = \frac{m_{o}v_{i_{o}} + m_{b}v_{i_{b}}}{m_{o} + m_{b}} = \frac{70.2 kg*0 + 0.400 kg*10.9 m/s}{70.2 kg + 0.400 kg} = 0.062 m/s [/tex]

Hence, Olaf and the ball will move at a speed of 0.062 m/s.

           

b) The final speed of Olaf after the collision can be calculated, again with conservation of linear momentum.

[tex] m_{o}v_{i_{o}} + m_{b}v_{i_{b}} = m_{o}v_{f_{o}} + m_{b}v_{f_{b}} [/tex]

In this case, since the ball hits Olaf and bounces off his chest, we have that [tex] v_{f_{o}} \neq v_{f_{b}}[/tex]

[tex] 0.400 kg*10.9 m/s = 70.2 kg*v_{f_{o}} + 0.400 kg*(-8.10 m/s) [/tex]      

The minus sign of the speed of the ball is because it moves to the negative direction of motion after the collision.  

[tex] v_{f_{o}} = \frac{0.400 kg*10.9 m/s + 0.400 kg*8.10 m/s}{70.2 kg} = 0.11 m/s [/tex]

Therefore, the speed of Olaf after the collision will be 0.11 m/s in the positive x-direction.                                  

 

You can see another example of conservation of linear momentum here: https://brainly.com/question/22257322?referrer=searchResults

   

I hope it helps you!                                                                                                                    

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