Describe the forces that are acting on a person who is standing still on a sidewalk and identify whether the forces are balanced or unbalanced. Describe how the forces would change if the person started walking.

Comedians like to joke that the reason we haven’t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earth’s broadcasts of intellectually embarrassing tv programs, like gilligan’s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. let’s check the assertion that aliens could have been receiving them. tv programs are broadcast at a frequency of about 100mhz with about 100kw of total power in 30frames per second, which emanatesroughly uniformly in all directions. assume that interstellar space transmits these broadcasts without attenuation. no matter how smart they are, aliens would require at least one photon per frame to interpret our signals. findthe number of photons per unit time per unit area reaching a receiver on a possible planet in the nearest star system, which is about 4 light-years away (a light-year is the distance light travels in a year). if aliens aimed a receiver or detector directly at earth, how big (in diameter) would it have to be to receive a photon per frame

Mass (kg) force (n) 5 25 10 50 15 75 20 100 a student was trying to find the relationship between mass and force. he placed four different masses on a table and pulled them using a spring scale. the table shows the different masses used in the experiment and the force required to pull each mass. the student concluded that more force was required to pull heavier objects. what comment would you make regarding his conclusion? a) no clear relation can be observed between mass and force from the data. b) there is a direct proportion between the mass and force listed in the table. c) gravity should have been taken into account while performing the experiment. d) there is an inverse proportion between the mass and force listed in the table.

Red’s momentum vector before the collision is green’s momentum vector after the collision. question 1 options: equal to shorter than longer than question 2 (1 point) saved since green bounces off red, this must be an collision. question 2 options: explosion elastic inelastic question 3 (1 point) red transfers of its momentum to green during the collision. question 3 options: none all little most question 4 (4 points) why does red transfer all its momentum to green? back up your answer with information from the simulation. write at least 2 sentences. question 4 options: skip toolbars for . more insert actions. more text actions. more paragraph style actions. question 5 (1 point) now make red much heavier than green. answer the questions below to describe how both red and green behave after the collision. question 5 options: slowed down sped up kept the same velocity question 6 (1 point) green sped up during the collision as it question 6 options: gained momentum from red lost momentum to red maintained a constant momentum. question 7 (1 point) after the collision . . question 7 options: both green and red moved to the right. both green and red stopped as they have lost all momentum. red stopped and green moved to the right. red bounced off green and went to the left. green moved to the right. question 8 (4 points) only some of red’s momentum was transferred to green. why did this occur? back up your answer with information from the simulation. write at least 2 sentences. question 8 options: skip toolbars for . more insert actions. more text actions. more paragraph style actions. question 9 (1 point) now make red much lighter than green. answer the questions below to describe how both red and green behave after the collision question 9 options: green sped up after the collision therefore it must have gained momentum. green sped up after the collision therefore it must have lost momentum. green slowed down after the collision therefore it must have gained momentum. green slowed down after the collision therefore it must have lost momentum. question 10 (1 point) since green gained momentum, red had to have momentum because you cannot create or destroy momentum. question 10 options: gained lost kept the same amount of question 11 (1 point) since green was so much and harder to move, it caused red to bounce back to the left giving red . question 11 options: heavier . . . . positive lighter. . . . negative lighter. . . . positive heavier . . . . negative question 12 (4 points) now, click on more data at the bottom of the sim. play with different numbers for the masses and starting velocities. you can even make the starting velocities negative! tell me one thing you discovered by adjusting the speeds and masses. write at least 2 sentences. be specific and use words like velocity, momentum, mass, increased, decreased, etc. 13. true or false: when red and green collide, they stick together. question 13 options: true false question 14 (1 point) the velocity of red & green after the collision is the velocity that red started off with. question 14 options: larger than smaller than equal to question 15 (1 point) the velocity after the collision was less because the mass has question 15 options: stayed the same decreased increased question 16 (1 point) the momentum before the collision was the momentum after the collision. question 16 options: larger than smaller than equal to conclusions question 17 (4 points) how are elastic and inelastic collisions different? give two or more ways. your answer should have at least 2 sentences. question 18 (4 points) give an example of a collision in real life. use the law of conservation of energy to describe the transfer of momentum. be sure and discuss the momentum before and after the collision occurs. you will need at least 3 sentences to thoroughly answer this question.