First step is to convert the lb to kg as follows:
1 lb = 0.45 kg
Therefore, 150 lb = 150 x 0.45 = 67.5 kg
Avogadro's number = 6.02 x 10^23
Mass of Avogadro's number of people = 6.02 x 10^23 x 67.5
= 4.0635 x 10^25 kg
Answer:
3.974 Joule
Explanation:
Diameter of ring = 7.7 cm
a = Distance from the center = d/2 = 3.85 cm = 0.0385 m
Q = Charge = 5 mC
q = Charge to move = 3.4 mC
k = Coulomb constant = 9×10⁹ Nm²/C²
Work done will be equal to Potential energy when mass is at center
![U=\frac{kQq}{a}\\\Rightarrow U=\frac{9\times 10^9\times 5\times 10^{-6}\times 3.4\times 10^{-6}}{0.0385}=3.974\ J](https://tex.z-dn.net/?f=U%3D%5Cfrac%7BkQq%7D%7Ba%7D%5C%5C%5CRightarrow%20U%3D%5Cfrac%7B9%5Ctimes%2010%5E9%5Ctimes%205%5Ctimes%2010%5E%7B-6%7D%5Ctimes%203.4%5Ctimes%2010%5E%7B-6%7D%7D%7B0.0385%7D%3D3.974%5C%20J)
∴ Work to move a tiny 3.4 mC charge from very far away to the center of the ring is 3.974 Joule
Question: A commuter backs her car out of her garage with an acceleration of 1.4 m/s² (a) How long does it take her to reach a speed of 2.00 m/s
Answer:
1.43 s
Explanation:
Applying,
a = (v-u)/t........... Equation 1
Where a = acceleration, v = final velocity, u = initial velocity, t = time
make t the subject of the equation
t = (v-u)/a........... Equation 2
From the question,
Given: v = 2 m/s, u = 0m/s (from rest), a = 1.4 m/s²
Substitute into equation 2
t = (2-0)/1.4
t = 1.43 s
A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.