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Subject Test Physics

Question 26 of 36

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SAT Subject Test

An object with mass m and speed v subscript 0 end subscript directed to the right strikes a wall and rebounds with speed v subscript 0 end subscript directed to the left.

The change in the object's momentum is

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2 m invisible times text     end text v subscript 0 directed to the left

Correct Answer: 
Yes

m invisible times text    end text v subscript 0 directed to the left

Correct Answer: 
No

text Zero end text

Correct Answer: 
No

m text     end text v subscript 0 directed to the right

Correct Answer: 
No

2 m invisible times text    end text v subscript 0 directed to the right

Correct Answer: 
No

The change in the object's momentum is 2 m invisible times v subscript 0 end subscript directed to the left. Momentum is a vector quantity. Its magnitude for an object of mass m and speed v is m v. Taking the positive direction to be to the right (the initial direction of the object), the object has momentum plus m v subscript 0 end subscript before striking the wall and momentum negative m invisible times v subscript 0 end subscript afterward. The change in momentum is the final value minus the initial value: negative m v subscript 0 end subscript minus left parenthesis plus m v subscript 0 end subscript right parenthesis equals negative 2 m invisible times v subscript 0 end subscript  

This is a change of magnitude 2 m invisible times v subscript 0 end subscript directed to the left.

Question Difficulty: 
hard