# Posts by bobjahng2

Total # Posts: 18

1. so the answer is A?
2. ### chemistry

55 25Mn can be prepared by electron capture from: (a) 55/24Cr (b) 55/26Fe (c) 56/25Mn (d) 51/23V (e) 56/26Fe
3. ### physics

The velocity of a particle constrained to move along the x-axis as a function of time t is given by: v(t)=-(15/t_0) sin(t/t_0). a)If the particle is at x=4 m when t = 0, what is its position at t = 4t_0. You will not need the value of t_0 to solve any part of this problem. b)...
4. ### physics

A laboratory centrifuge on earth makes n rpm (rev/min) and produces an acceleration of 3.30 g at its outer end. This centrifuge is now used in a space capsule on the planet Mercury, where g mercury is 0.378 what it is on earth. How many rpm (in terms of n) should it make to ...
5. ### chemistry

The given reaction, cyclopropane propene (isomerization), follows first-order kinetics. The half-live was found to be 4.57 min at 796 K and rate constant was found to be 0.0328 s-1 at 850 K. Calculate the activation energy (in kJ/mol) for this reaction. Round your answer to 3 ...
6. i don't get the right answer. Plus arent we missing A?
7. ### chemistry

The reaction, cyclopropane propene (isomerization), was observed to have rate constants k = 0.000213 s-1 at 477 °C and k = 0.0328 s-1 at 577 °C. What is the value of Ea expressed in kJ mol-1? Round your answer to 3 significant figures.
8. ### chemistry

follows first-order kinetics and has an activation energy of 244 kJ mol-1. At 684 K, k = 0.00000508 s-1. What is the half-life (min) for this reaction at 427 °C ? Round your answer to 3 significant figures. I really don't know what to do
9. ### physics

You are watching an archery tournament when you start wondering how fast an arrow is shot from the bow. Remembering your physics, you ask one of the archers to shoot an arrow parallel to the ground. Unfortunately the archer stands on an elevated platform of unknown height. ...
10. ### physics

How far from the origin is the puck after 5 seconds (m)? Since I cant post internet sites, The vx graph starts at the origin and has a slope of +8. The vy graph has a slope of 0 and starts at 30. The y axis is in cm/s and I am looking for total distance in meters. Thanks =]
11. uhhhh so i understand everything you did, but i am having issues with the algebra. Any tips/hints?
12. ### physics

In the latest Indian Jones film, Indy is supposed to throw a grenade from his car, which is going 79.0 km/h, to his enemy's car, which is going 102 km/h. The enemy's car is 14.3 m in front of the Indy's when he lets go of the grenade. If Indy throws the grenade so ...
13. nvm i got it. Thanks for the help
14. is Ac^- equal to to 20 ml x the concentration? if so then I am getting the wrong answer according to my answer sheet. By the way what would my total volume be?
15. I understand everything except for part d. Could you show me what you mean by writing the k expression.
16. ### chemistry

Consider a 20.0mL sample of 0.105M HC2H3O2 is titrated with 0.125M NaOH. Ka=1.8x10^-5. Determine each of the following: a) the initial pH b) the pH at 5.0mL of added base c) the pH at one-half of the equivalence point d) the pH at the equivalence point
17. ### physics

A projectile is launched from ground level to the top of a cliff which is 195 m away and 135 m high.If the projectile lands on top of the cliff 6.5 s after it is fired, find the initial velocity of the projectile ( (a)magnitude and (b)direction ). Neglect air resistance.
18. ### physics

A projectile is launched from ground level to the top of a cliff which is 195 m away and 135 m high.If the projectile lands on top of the cliff 6.5 s after it is fired, find the initial velocity of the projectile ( (a)magnitude and (b)direction ). Neglect air resistance.