Question

I have tried to answer these questions but I just don't get it, they are my last questions of the year and I just want to be done! Can you please help me and explain them? Thanks!
16. You are in a car going 70 km/h and another car passes you going in the opposite direction at 70 km/h. Do both cars have the same velocity? Explain.
18. You push on a crate with a force of 10 N to the right, and your friend pushes on the crate with a force of 25 N to the left. Describe and explain the motion of the crate.
21. An inventor claims to have built a machine that can produce 120 J of work with

Answer 1

16) Velocity has both a direction and a magnitude. Both cars have the speed (magnitude of velocity) but because their directions are different, the velocity's are different.

18) You have to find the net force on the crate. Since the forces are in opposing directions the net force will be:
\[Fnet=F1−F2=25N−15N=15N\]The motion will be in the direction in which the larger force is pushing.

21) Missing information.

Answer 2

*correction: "both cars have the _same_ speed". I left out a word there.

Answer 3

Please post the rest of question 21 :)

Answer 4

Thanks a ton for the first questions! That helps so much! Here is the rest of 21, not sure why it didn't go on the first time!
21. An inventor claims to have built a machine that can produce 120 J of work with an input of 110 J. Would you believe the inventor's claim? Why or why not

Answer 5

Since the law of thermodynamics states that energy can neither be created nor destroyed if you have an input of 110J there is no way you can produce more than 110J of work. So the answer is no i would not believe the inventor due to the law of thermodynamics

Answer 6

I wouldn't believe the inventor because the invention would break the law of conservation of energy which says that energy cannot be created or destroyed.

Answer 7

Ok got it! You just helped so much, thank you!!!! :D

Answer 8

No worries :)