Physics final coming up.. Help wanted please?

Question

I have a physics final tomorrow and physics is definitely my absolute worst subject and we got a review packet which I answered most of but I want to find out if i got the right answers. Any help would be greatly appreciated.
1. Suppose you are driving your car down the highway at constant velocity. Which of the following are true?
a) the car's momentum is constant but not its kinetic energy
b) the car's kinetic energy is constant but not its momentum
c) both the car's kinetic energy and momentum are constant
d) neither the car's kinetic energy nor momentum are constant

2. suppose you are a football player and you kick a ball for a field goal. ignoring air resistance, the ball's horizontal velocity
a) changes throughout the path due to gravitational acceleration
b) is zero at the top of the path
c) is maximum at the top of the path
d) remains constant throughout the path

3. which of the following does NOT radiate heat?
a) a burning bush
b) a cup of coffee
c) an ice cube
d) a piece of metal a .00001 K degrees
e) None of the above

4) wind is one of nature's ways of transferring energy through
a) conduction
b) convection
c) transmission
d) radiation

5. einstein's theory of relativity is based in part on which one of the following postulates?
a) mass and energy are equivalent
b) space and time are absolutes
c) energy is conserved only in elastic collisions
d) speed of light in a vaccum is same for all observers regardless of source velocity

6. the observed relativistic length of a super rocket moving by the observer at .70c will be what factor times that of the measured rocket length if it were at rest?
a) 0.45
b) 0.71
c) 0.82
d) 1.4

7. which of the following is fundamentally different from the others
a) x-rays
b) sound waves
c) light waves
d) radio waves
e) gamma rays

8. Uranium-238 decays to thorium-234 by emitting which of the following?
a) beta
b)alpha
c) gamma
d) positron

9. when radium-224 emits an alpha particle, the remaining daughter nucleus is which of the following?
a) lead-213
b) actinium-215
c) radon-220
d) bismuth-215

10. of the main types of radiation emitted from naturally radioactive isotopes, which of the following is the most penetrating
a) alpha
b) beta (electron)
c) gamma
d) beta (positron)

These are just some of the ones i am having trouble with, especially the last 3. If you could provide an explanation for the answers that would be even better. Thanks to all those who help me out.

Answer 1

Last three it is...



"8. Uranium-238 decays to thorium-234 by emitting which of the following?"

b)alpha

... the change in nucleons is 4 (238 - 234), and an alpha particle is 4 nucleons.



"9. when radium-224 emits an alpha particle, the remaining daughter nucleus is which of the following?"

c) radon-220

... only one choice is 4 less.



"10. of the main types of radiation emitted from naturally radioactive isotopes, which of the following is the most penetrating?"

c) gamma

... under any circumstances.

Answer 2

1 c

2 d

3 c

4 b

5 a

6

7 b

8 c

9 c

10 c

Answer 3

you're assuming a connection the position there is none. merely because the speed will boost by technique of a given quantity each and every second does not recommend that the area has to extend by technique of that similar quantity. Having a particular acceleration at a given time places no limit on the speed on the instantaneous. Acceleration isn't the speed at which the area is replacing, it really is the speed at which the speed at which the area is replacing is replacing.