# Physics

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I really need help with only this two problems.

1. A 6.0 kh block, sliding to the east across a horizontal, frictionless surface with a momentum of 30 kg*m/s^, strikes an obstacle. The obstacle exerts an impluse of 10 N*s to the west on the book. The speed of the block after the collision is...

2. While riding a chairlift, a 55 kg skier is raised a vertical distance of 370 m. what is the total change in the skier's gravitional potential energy? given: m = 55 kg d = 370 m When i used PE = mgh, the answer was 199,430, i know its wrong since the answer is something else. But what equation can i use?

• Physics -

1. Is kh supposed to be kg? Are the block and the book the same object?

Whatever. The applied impulse equals the reduction in momentum of the block/book.

2. Your answer is correct and you used the right equation. Perhaps they want you to use only two significant figures (200,000 J) which is the same number of significant figures as the 9.8 m/s^2 and the 55 kg). You also must include the units (J) in your answer.

• Physics -

Ok, i understand question 2, i realize what i did wrong. But i don't understand question 1.

• Physics -

Ok thanks. Yes, for question 1, its 6 kg, sorry.

• Physics -

yes, is it j = m(change)v that i have to use for question 1

• Physics -

No, theres no book in this question only block.

• Physics -

<<The obstacle exerts an impulse of 10 N*s to the west on the book.>>

Looks like "book" to me

The impulse equals the momentum change, which is M times the velocity change

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