A Physics Challenge Can you answer all 13 questions?

[Totalwar 0]

This weekend I found my self unable to post due to my fianc? having a physics test on Monday (today). I spent the weekend typing out physics problems for her to solve and now I give them to you. I challenge anyone in the Trap 17 forums to answer all 13 questions. Feel free to use any resources the vast internet has to offer. So common you physics enthusiasts out there, make yourselves known!1) At exactly noon an object has a displacement of ?30m. At exactly 5 seconds after noon the object has a displacement of ?50m. Find the average velocity of the object over the time interval beginning at noon and ending at 5 seconds after noon.2) At exactly 5pm an object has a displacement of ?100m. At exactly 25 seconds after noon the object has a displacement of ?25m. Find the average velocity of the object over the time interval beginning at noon and ending at 5 seconds after noon.3) An object is traveling with a constant velocity. Initially the object is 20m East of the tree. Five seconds after the initial time the object is 10m west of the tree. Find the speed of the object.4) An object is traveling with a constant velocity. Initially the object is 60m East of the tree. Ten seconds after the initial time the object is 10m west of the tree. Find the Velocity of the object, then find the speed. Are these values the same or different and why?5) A ball is launched vertically upwards from the ground with a speed of 60 m/s. When will the ball have a speed of 40m/s? (assume the only force on the object is gravity)6) A rock is launched vertically upwards from the ground with a speed of 100 m/s. When will the ball have a Velocity of 40m/s? When will it have a speed of 40m/s? (assume the only force on the object is gravity, and that upwards is positive while down is negative). Are these values the same or different and why.7) A cannon ball is fired from the ground at an angle of 45 degrees. The cannon ball leaves the cannon with a speed of 200√2m/s. What is the speed of the ball 10 seconds after the ball is fired? What is the maximum height of the ball? Where will the ball hit the ground? (Assume gravity is the only force on the ball.)8) A rock is fired from the ground at an angel of 45 degrees. The rock is launched at a speed of 50√2m/s. What is the speed of the ball 2 seconds after it is fired? What is the maximum height of the ball? Where will the ball hit the ground?9) Bob and sue are standing on ice (assumed to be frictionless). Bob Weighs 500N. They push against each other and Sue acquires an acceleration of magnitude 5m/s^2 while Bob acquires an acceleration of 3m/s^2. Find Sue?s Mass10) Karl and Nick are standing on ice (assumed to be frictionless). Karl weighs 100N. They push against each other and Nick acquires an acceleration of magnitude 10m/s^2 while Karl acquires an acceleration of 5m/s^2. Find Nicks mass.11) During a football game Jeff is forced to Kick a field goal. He is 40 meters from the goal post and the goal post is 5 meters high. What are the necessary vertical and horizontal speeds Jeff will need to hit the ball with in order to make the field goal?12) You decide to drive your car off a vertical ramp at 80mph. Assuming you?re a launched vertically into the air at 80mph and that gravity is the only force acting on your car, how long will your car be in the air? What will be your car?s maximum height?13) At the end of the semester you decide to drop your physics book off the edge of the grand canyon. The grand canyon is 1 mile deep. How long will it take for you book to hit the bottom of the canyon? How fast will your book be traveling, in miles per hour, just before it hits the ground?

[Saint_Michael 3]

aaah!! just reading is killing off my brain cells and the fact you have to use some math just makes it even worse ***falls to floor rolling around mumbling to self about e=mc2***

[snlildude87 0]

aaah!! just reading is killing off my brain cells and the fact you have to use some math just makes it even worse ***falls to floor rolling around mumbling to self about e=mc2***

165563[/snapback]

Uhh, all the problems are kinematics. e = mc^2 is energy. Are you sure you're 23?

 

I can solve these problems, but I'm too lazy to reach for my calculator (where my equations are stored). I'll solve this later. By the way, do these include calculus?

[Saint_Michael 3]

oh i am, let just say that i would hae an extremely hard time with this, since math is one of my weaker subjects, anything above algebra is like beyond me.oh i know that ijust to telling you how fried my brain is after reading all that, plus i was never good at world problems i prefer the direct equation, it just makes my life simple.

[rvalkass 5]

We've just been doing velocity and all that, but it's currently the holidays, so school has taken a much needed trip with very high velocity out of the window.BTW is the answer to 3) 6 metres per second ??? It just looked the easiest.

[emperor 0]

No, physic! Please doesn't tell about this terrible subject. It's the subject where I've the bad mark (7/10, orrible). Why can't you make some question about biology, hystory or italian literature? Anyway you question doesn't seem to be so terrible, if I will suicide, i will remember you Totalwar.

[canpolitics 0]

1) Average velocity is -4m/sec2) Tricky one, but I am assuming you are talking about the same day, as such there are 17975 seconds between 25 seconds after noon and exactly 5pm. So I get a calculation of aprox -15m/hr (not sure about my calcs on that one, and too lazy to double check )3) 6m/sec4) Nice one, throw in a trick of speed vs. velocity... the speed is 7m/s the velocity is the same. If I remember my physics classes the primary difference between speed and velocity is that velocity takes direction into account (or some such thing)5) This is just a quick calc so it is just a rough estimate, but I think it is after 2 seconds and again possibly at 10 seconds (on the way down)no more time to work on these.... interested to know if my physics memory is right at all?

[Totalwar 0]

I'll post some answers this weekend along with some explinations. And for those of you who said you don't like physics, don't worry, my fience just got her test back and she got a 70%, so your not alone.

[Anndi 0]

I've never taken Physics before. But the answer to question one is easy; -4m/s, right? But I stopped when I read question two. I'll come back one day when it's not so late and figure out the rest!

[moonwitch 0]

1. Since the total displacement is 20m in 5 seconds, that would make the velocity 4m/s, (and velocity should be expressed in km/hr here so 14.4km/hr)2. Average speed over 5 seconds is impossible to calculate, too little info to do it accurately. Over the total distance, -3m/s. (the object slows down or thurned around to return on it's previous path) so in km/hr -10.8km/hr3. The object travels 30m in total, in 5 s. So 30m/5s = 6m/s or 21.6km/hrOK I got tired of it LOL Physics is not my best course, especially not kinematics. Warmth is nicer

[cse-icons 0]

hi Totalwarhere are a few of my answers:1) 4 m/s3) speed = 6 m/s4) speed = 7 m/s velocity is a vector and takes direction into account so it would be 5 m/s (I do not remeber whether velocity need to be in km/hr in which case it should be multiplied by 18/5)Actually these problems were my forte when I was in school. but has been a few years since and also I am feeling lazy now.. would solve and post a few more answers later..btw it was nice of u to put in effort for the questions... (though u did it for ur fiance.. :DCheers.

[Totalwar 0]

1) At exactly noon an object has a displacement of 30m. At exactly 5 seconds after noon the object has a displacement of 50m. Find the average velocity of the object over the time interval beginning at noon and ending at 5 seconds after noon.
2) At exactly 5pm an object has a displacement of 100m. At exactly 25 seconds after noon the object has a displacement of 25m. Find the average velocity of the object over the time interval beginning at noon and ending at 5 seconds after noon.

3) An object is traveling with a constant velocity. Initially the object is 20m East of the tree. Five seconds after the initial time the object is 10m west of the tree. Find the speed of the object.

4) An object is traveling with a constant velocity. Initially the object is 60m East of the tree. Ten seconds after the initial time the object is 10m west of the tree. Find the Velocity of the object, then find the speed. Are these values the same or different and why?

5) A ball is launched vertically upwards from the ground with a speed of 60 m/s. When will the ball have a speed of 40m/s? (assume the only force on the object is gravity)

6) A rock is launched vertically upwards from the ground with a speed of 100 m/s. When will the ball have a Velocity of 40m/s? When will it have a speed of 40m/s? (assume the only force on the object is gravity, and that upwards is positive while down is negative). Are these values the same or different and why.

7) A cannon ball is fired from the ground at an angle of 45 degrees. The cannon ball leaves the cannon with a speed of 200√2m/s. What is the speed of the ball 10 seconds after the ball is fired? What is the maximum height of the ball? Where will the ball hit the ground? (Assume gravity is the only force on the ball.)

8) A rock is fired from the ground at an angel of 45 degrees. The rock is launched at a speed of 50√2m/s. What is the speed of the ball 2 seconds after it is fired? What is the maximum height of the ball? Where will the ball hit the ground?

9) Bob and sue are standing on ice (assumed to be frictionless). Bob Weighs 500N. They push against each other and Sue acquires an acceleration of magnitude 5m/s^2 while Bob acquires an acceleration of 3m/s^2. Find Sues Mass

10) Karl and Nick are standing on ice (assumed to be frictionless). Karl weighs 100N. They push against each other and Nick acquires an acceleration of magnitude 10m/s^2 while Karl acquires an acceleration of 5m/s^2. Find Nicks mass.

11) During a football game Jeff is forced to Kick a field goal. He is 40 meters from the goal post and the goal post is 5 meters high. What are the necessary vertical and horizontal speeds Jeff will need to hit the ball with in order to make the field goal?

12) You decide to drive your car off a vertical ramp at 80mph. Assuming youre a launched vertically into the air at 80mph and that gravity is the only force acting on your car, how long will your car be in the air? What will be your cars maximum height?

13) At the end of the semester you decide to drop your physics book off the edge of the grand canyon. The grand canyon is 1 mile deep. How long will it take for you book to hit the bottom of the canyon? How fast will your book be traveling, in miles per hour, just before it hits the ground?

1) -4 m/s

2) Sorry there was a typo in this one, it should have said at exactly 25 seconds after 5pm. If thats the case, the answer is 3 m/s

3) 6m/s

4) V=-7m/s S=7m/s, these values are different because speed has an absolute value (it cant be negative)

5) 2 seconds

6) V=40 m/s when t=14 and when t=6, S=40m/s when t=6 (assuming up is positive).

7) S=223.61m/s, maximum height = 2000m, the ball will land 8000m from the launch site.

8) Speed = 58.31m/s, Maximum height = 80m, the ball will land 500meters from the launch site.

9) Sues mass is 30kg

10) Nicks mass is 5kg

11) The ball must be kicked with a horizontal speed of 40m/s and a vertical speed of 10m/s.

12) The car will be in the air 6 seconds and reach a maximum height of 500m

13) Your book will fall for 17.9 seconds and reach a maximum speed of 358mph (ignoring wind resistance).

[BuffaloHelp 24]

5)  2 seconds

 

6)  V=40 m/s when t=14 and when t=6, S=40m/s when t=6 (assuming up is positive).

 

7)  S=223.61m/s, maximum height = 2000m, the ball will land 8000m from the launch site.

 

8)  Speed = 58.31m/s,  Maximum height = 80m, the ball will land 500meters from the launch site.

 

9)  Sue?s mass is 30kg

 

10)  Nicks mass is 5kg

 

11)  The ball must be kicked with a horizontal speed of 40m/s and a vertical speed of 10m/s.

 

12)  The car will be in the air 6 seconds and reach a maximum height of 500m

 

13)  Your book will fall for 17.9 seconds and reach a maximum speed of 358mph (ignoring wind resistance).

167658[/snapback]

Starting from answers #5 and on, I think you rounded off too much. According to significant numbers, you should have at least 2 places or one decimal place because gravity = 9.8m/s^2 so there are two significant places. Answer #5 has one (should be 2.05 or 2.1 seconds). Answer #6 has one (should be 6.1 and 14.3 seconds)...etc.

 

I hope the students weren't tested for significant places...

[Zaccid 0]

Oh my ... with the way my head is feeling right now there is no way that I could understand them questions :shock: Oh well I surpose that happens and I will have to come back here later and re-do this one again when my head is more with it.

[Totalwar 0]

Thanks for your answers guys, and yes in her class they round gravity to 10m/s^2 in order to simplify the math. She's taking another test today regarding Gravitational Potential Energy and Kinetic Energy. I made a review sheet for that as well but judging from the general dislike of physics most people have I?ll only post them if anyone thinks they can answer them. Oh what the hay, here?s an example problem. A single force is applied to an object. The object?s initial kinetic energy is 500 Joules. The force does 600 Joules of work. What is the final kinetic energy of the object? What is the change in kinetic energy of the object?