students have two samples of uranium that they know were pure at some point in the past, and they wanted to determine which sample is older. an analysis reveals the percentage of uranium-238 and lead 206 contained in each sample, as shown in the circle graphs. based on these data as well as the uranium 238 decay series, which sample can the students conclude is older?​

(01.02 mc) nicole pushes her bike up a hill. overhead, the sun exerts a gravitational force on earth. which statement is true about the bike and earth? they both experience contact forces. they both experience non-contact forces. the bike experiences a non-contact force and earth experiences a contact force. the bike experiences a contact force and earth experiences a non-contact force. they both experience non-contact forces.

10 points! will mark brainiest! in a heat engine if 1,000 j of heat enters the system and the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2,000 j 1: write the equation2: list out your known variables 3: plug the numbers into the equations 4: solve 5: write your solution statement that includes initial energy and final energy added you so much!

What is a subatomic particle with a negative charge and very little mass?