Answer:
The second knife-edge must be placed 46.2 cm from the zero mark of the rod.
Explanation:
From the law of equilibrium, ΣF = 0 and ΣM = 0.
Let R be the reaction at the knife edge. Since the weight of the rod and zinc load act downward, and we take downward position as negative
-32 N - 2 N + R = 0
-34 N = -R
R = 34 N
Also, let us assume the knife-edge is x cm from the zero mark. Taking moments about the weight and assuming the knife-edge is right of the weight of the rod. Taking clockwise moments as positive and anti-clockwise moments as negative,
-(45 - 25)2 + (x - 45)R = 0
-(20)2 + (x - 45)34 = 0
-40 = -(x - 45)34
x - 45 = 40/34
x - 45 = 1.18
x = 45 + 1.18
x = 46.18 cm
x ≅ 46.2 cm
The second knife-edge must be placed 46.2 cm from the zero mark of the rod.
Answer: The correct answer is option (B).
Explanation:
Law of conservation of mass: 'In a chemical reaction, mass neither be created nor be destroyed'
In the balance chemical equation,total mass of the reactants is equal to the total mass of the products.
A. 
![[2\times (23 g/mol)+(35.5 g/mol)\times 2]=[23 g/mol+35.5 g/mol]](https://tex.z-dn.net/?f=%5B2%5Ctimes%20%2823%20g%2Fmol%29%2B%2835.5%20g%2Fmol%29%5Ctimes%202%5D%3D%5B23%20g%2Fmol%2B35.5%20g%2Fmol%5D)
117 g/mol ≠ 58.5 g/mol
Law of Conservation of Mass not followed.
B.
![[2\times (23 g/mol)+(35.5 g/mol)\times 2]=2\times [23 g/mol+35.5 g/mol]](https://tex.z-dn.net/?f=%5B2%5Ctimes%20%2823%20g%2Fmol%29%2B%2835.5%20g%2Fmol%29%5Ctimes%202%5D%3D2%5Ctimes%20%5B23%20g%2Fmol%2B35.5%20g%2Fmol%5D)
117 g/mol = 117 g/mol
Law of Conservation of Mass is followed.
C.
![[2\times (23 g/mol)+(35.5 g/mol)\times 2]=2\times [23 g/mol+35.5 g/mol]](https://tex.z-dn.net/?f=%5B2%5Ctimes%20%2823%20g%2Fmol%29%2B%2835.5%20g%2Fmol%29%5Ctimes%202%5D%3D2%5Ctimes%20%5B23%20g%2Fmol%2B35.5%20g%2Fmol%5D)
188 g/mol ≠ 117 g/mol
Law of Conservation of Mass not followed.
D.
![[(23 g/mol)+(35.5 g/mol)\times 2]=2\times [23 g/mol+35.5 g/mol]](https://tex.z-dn.net/?f=%5B%2823%20g%2Fmol%29%2B%2835.5%20g%2Fmol%29%5Ctimes%202%5D%3D2%5Ctimes%20%5B23%20g%2Fmol%2B35.5%20g%2Fmol%5D)
94 g/mol ≠ 117 g/mol
Law of Conservation of Mass not followed.
Hence, the correct answer is option (B).
Setting reference frame so that the x axis is along the incline and y is perpendicular to the incline
<span>X: mgsin65 - F = mAx </span>
<span>Y: N - mgcos65 = 0 (N is the normal force on the incline) N = mgcos65 (which we knew) </span>
<span>Moment about center of mass: </span>
<span>Fr = Iα </span>
<span>Now Ax = rα </span>
<span>and F = umgcos65 </span>
<span>mgsin65 - umgcos65 = mrα -------------> gsin65 - ugcos65 = rα (this is the X equation m's cancel) </span>
<span>umgcos65(r) = 0.4mr^2(α) -----------> ugcos65(r) = 0.4r(rα) (This is the moment equation m's cancel) </span>
<span>ugcos65(r) = 0.4r(gsin65 - ugcos65) ( moment equation subbing in X equation for rα) </span>
<span>ugcos65 = 0.4(gsin65 - ugcos65) </span>
<span>1.4ugcos65 = 0.4gsin65 </span>
<span>1.4ucos65 = 0.4sin65 </span>
<span>u = 0.4sin65/1.4cos65 </span>
<span>u = 0.613 </span>
Answer:
b)
Explanation:
By convention, the electric field lines (which are tangent to the direction of the electric field at a given point) always begin at positive charges, and finish at negative charges.
This is a consequence of the convention that states that the electric field has the direction of the trajectory of a positive test charge when released from rest in an electric field.
(As the positive charge would move away from positive charges and would be attracted by negative ones).
So, the combination of answers that is true is b) (positive, negative, positive).