BIOLOGY homework help!!?
1) It's obvious why this is important- your body needs to be able to fight infection, which is caused by foreign pathogens entering your body. If it could not distinguish between friend and foe, the possibility would exist that it would either not do anything at all, or attack your own cells because it didn't know any better. (an autoimmune disease) 2.) Multiple Sclerosis is an autoimmune disorder in which macrophages of the immune system attack the myelin sheath of central nervous system nerve axons, causing demyelination of the nerve. This slows down signal transduction and impulse propogation, causing paralysis and weakening of muscles. Rheumatoid arthritis is another condition in which the cells of the immune system attack joint and bone tissue, causing spurs to develop and joint to fuse, resulting in decreased movement and eventually freezing of body joints like knuckles and wrists.
I need help on these homework for my test!?
1) Determine the number of Kr atoms in a 5.20mg sample of krypton. 2) Determine the molar mass, M, of an element if the mass of a 2.80x10^22 atom sample of the element is 2.09g. 3) Determine the identity of an element if the mass of a 2.80x10^22 atom sample of the element is 2.09g. (multiple choice) a)scandium b)calcium c) titanium d) potassium 4)Determine the mass of a sample of phosphorus that contains the same number of atoms as 44.80 g of magnesium.
Help with Newton's Third Law homework?
To review, here are Newton's Three Laws of Motion: 1) Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. 2) The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector. 3) For every action there is an equal and opposite reaction. ****************** 1. Identify which of newtons three laws of motion specifically applies in each of the following situations.. a. You feel a force against the sole of your foot as you take a step forward (Law # 3) b. A meteor moving in a straight path changes directions when it flies by earth (Law # 1) c. A full grocery cart that is pushed starts moving and increases speed, but the same push increases its speen even more when the cart is empty. (Law # 2) d. A skateboard moves faster in the same direction it is pushed. (Law # 2) 3. Momentum is mass x velocity. The train's mass is much larger than that of the bullets. So, a bullet will have to be moving very fast in order to have the same momentum as a slow moving train. 4. Just multiply mass x velocity in each case and compare the answer. For example, a 500 kg car moving at 65 km/h would have a momentum of 500 x 64 kg km / h = 32000 kg km / h 5. Since the momentum is mass x velocity, and the mass of the car is constant, the velocity is constant.
Chemistry 111 Homework problem please teach me step by step i can't get it right!?
first sampel 0.66 g of Y and 0.34 g of X second sample 0.56 g of Y and 0.44 g of X ratio of ratios so to speak: (.66/.34)/(.56/.44) = 1.52 most likely 1.5 ============= first choice ratio of ratios is 2/4 *3/1 = 1.5 BINGO 2nd choice 1/1 * 2/1 = nno 3rd 1/2 * 3/1 = 1.5 BINGO (note that X4Y2 and X2Y have same empirtical formula) 4th 1/3 * 4/1 no 5ht no 6th no 7th 5/2 * 3/5 = BINGO choices 1, 3, 7 ratio
NEED HELP TO CALRIFY MATH PROBLEM!!?
Well if you've completed the square then you have the form: (x-h)^2 + k = 0 then the max or min would occur at x=h, and the min/max value is k. x^2 - 3x + 5 = 0 x^2 -3x + 9/4 = -5 + 9/4 (x -3/2)^2 = -11/4 (x -3/2)^2 + 11/4 = 0 so x=3/2 is a line of symettry. Its min. value is 11/4. It's a minimum because the coeffecient of x^2 is 1, which is positive, so it's an U shaped (concave up) parabola. It has no real roots since the min. value is larger than 0. For the last question -3x^2-4x+15 = 0 -3(x^2 + 4/3x)=-15 -3(x^2 + 4/3x + [(1/2)(4/3)]^2) = -5 + (-3*16/35) -3(x+2/3)^2+16+1/3=0 so max. value of 16+1/3. Axis of symettry x=-2/3. Max point (-2/3, 16+1/3)
AP Physics summer assignment?
Uh oh, you had all summer to work on this problem and you're just now getting to it? (I've been there, lol!) (a) Show that V=Ah is dimensionally correct. V = volume, in units of length^3 (e.g. V = 5in^3) A = area, which is in units of length * length, or length^2 Example, the area of a checkerboard with 1 inch squares is 8in x 8 in = 64 in^2 H = height, in units of length. So, the units of (A * H) is equal to (length^2) x* length = length^3 These are the same units as V, so V = A*H. The units on both sides of the equation are the same. b) Part 1: Volume of a cylinder = pi * (r^2) * h But the term pi * (r^2) is equal to the circular cross-sectional area of the cylinder. That is, A = pi * (r^2) So, we can replace that term with ‘A’ in the equation above to get V = pi * (r^2) * h V = A * h <= = Answer b) Part 2: Volume of a rectangular box. V = (length * width) * height But length * width equals the cross-sectional area of the box that is in contact with the table-top, or: A = length * width Substituting into the equation above, V = (length * width) * height V = A * h <= = Answer Hope this helps, -Guru
1 Math Question>>>10 Points Rewarded?
Find the exact value of each of the following. In each case, show your work and explain the steps you take to find the value. 1. sin 17pi/6 2. tan 13pi/4 3. sec 11pi/3