Unit Vectors and Momentum Changes in a Block of Ice

[Troi Jones]

Homework Statement

A 0.5 kg block of ice is sliding by you on a very slippery floor at 2.5 m/s. As it goes by, you give it a kick perpendicular to its path. Your foot is in contact with the ice block for 0.0035 seconds. The block eventually slides at an angle of 24 degrees from its original direction (labeled θ in the diagram). The overhead view shown in the diagram is approximately to scale. The arrow represents the average force your toe applies briefly to the block of ice. (Only components involved are x and z, as shown in the picture.)

Homework Equations

delta p= Fnet*delta t
p= m*v
Pythagorean theorem possibly?
Trigonometry

The Attempt at a Solution

Which components of the block's momentum are changed by the impulse applied by your foot? (Check all that apply. The diagram shows a top view, looking down on the xzplane.)[/B]
Its the z component that only changes. The kick was perpendicular to the momentum in the + x direction, so x is not effected.

What is the unit vector in the direction of the block's momentum after the kick?
Not really sure what this question is saying. I know that in the vector the x component will be positive and the z component will be negative, but I'm lost of how to find the momentum for z...What is the x-component of the block's momentum after the kick?
Stated earlier, x component wasn't affected, so the momentum is still 1.25 kg*m/s

Remember that

= |

|p̂. What is the magnitude of the block's momentum after the kick?

Can't do this problem without that unit vector in question 2

Use your answers to the preceding questions to find the z-component of the block's momentum after the kick (drawing a diagram is helpful):

pfz = ? kg · m/s

What was the magnitude of the average force you applied to the block?

|

avg| = ? N

It be much obliged to have some guidance to solve the questions that are blank

 

[kuruman]

... (labeled θ in the diagram). The overhead view shown in the diagram is approximately to scale.

What diagram? What picture?

 

[Troi Jones]

What diagram? What picture?

sorry though I posted it. The correct diagram to look at is B

 

[kuruman]

Not really sure what this question is saying. I know that in the vector the x component will be positive and the z component will be negative, but I'm lost of how to find the momentum for z...

You are asked to find a vector of magnitude 1 that points at angle θ below the positive x-axis. Draw it and then find its components.

 

[Troi Jones]

You are asked to find a vector of magnitude 1 that points at angle θ below the positive x-axis. Draw it and then find its components.

Could you please elaborate on how you know the vector magnitude is 1 and how do you know the vector is pointing at theta below the +x-axis?

 

[kuruman]

Could you please elaborate on how you know the vector magnitude is 1 ...

I know because a unit vector by definition has magnitude 1.
https://en.wikipedia.org/wiki/Unit_vector

... and how do you know the vector is pointing at theta below the +x-axis?

I know because I looked at the picture that you posted.

 

[Troi Jones]

Homework Statement

A 0.5 kg block of ice is sliding by you on a very slippery floor at 2.5 m/s. As it goes by, you give it a kick perpendicular to its path. Your foot is in contact with the ice block for 0.0035 seconds. The block eventually slides at an angle of 24 degrees from its original direction (labeled θ in the diagram). The overhead view shown in the diagram is approximately to scale. The arrow represents the average force your toe applies briefly to the block of ice. (Only components involved are x and z, as shown in the picture.)

Homework Equations

delta p= Fnet*delta t
p= m*v
Pythagorean theorem possibly?
Trigonometry

The Attempt at a Solution

Which components of the block's momentum are changed by the impulse applied by your foot? (Check all that apply. The diagram shows a top view, looking down on the xzplane.)[/B]
Its the z component that only changes. The kick was perpendicular to the momentum in the + x direction, so x is not effected.

What is the unit vector in the direction of the block's momentum after the kick?
Not really sure what this question is saying. I know that in the vector the x component will be positive and the z component will be negative, but I'm lost of how to find the momentum for z...What is the x-component of the block's momentum after the kick?
Stated earlier, x component wasn't affected, so the momentum is still 1.25 kg*m/s

Remember that View attachment 218607 = |View attachment 218608|p̂. What is the magnitude of the block's momentum after the kick?

Can't do this problem without that unit vector in question 2

Use your answers to the preceding questions to find the z-component of the block's momentum after the kick (drawing a diagram is helpful):

pfz = ? kg · m/s

What was the magnitude of the average force you applied to the block?

|View attachment 218609avg| = ? N

It be much obliged to have some guidance to solve the questions that are blank

Update: I got the answer wrong. My answer was < 0.4242,0, -.9056>. The solution was <0.914,0, -0.407>. Not quite sure how to get to that answer but anyone feel free to explain if you understand.

 

[kuruman]

I can explain if you first explain how you got your answer. How can I determine where you went wrong without knowing what you did?