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Test corrections

  • #1
Test corrections!!!!

Homework Statement


1.) a railroad car of mass m is moving with speed v when it collides with and connects to a second railroad car of mass 3m, initially at rest. how do the speed and kinetic energy of the connected cars compare to those of the single car of mass m before the collision.
speed/Kinetic Energy
a.)less,less​
b.)less,the same​
c.) the same, less​
d.) greater, the same​

2.) a ball of mass m and momentum p has kinetic energy equal to which of the following?
a.) 1 p2/2 m​
b.) p2/m​
c.)2 (p2/m)​
d.)1m/2p2

3.) a new planet is discovered that is twice the Earth's mass and twice the Earths radius. On the surface of this new planet, a person who weights 500N on earth would experience a gravitational force of
a.)125N​
b.)250N​
c.)500N​
d.)1000N​

Homework Equations





The Attempt at a Solution


1 is not b
2 is not b
3 is not c
 

Answers and Replies

  • #2
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,252
970


What have you tried?

Where are you stuck?

Can you give any reasons as to why the listed answers are wrong?

A hint for #2: What is the formula for p? Pk\lug that formula in for p in the four choices. See if any of them result in the formula for kinetic energy.
 

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