Answer:
a) 2.87 m/s
b) 3.23 m/s
Explanation:
The avergare velocity can be found dividing the length traveled d by the total time t.
a)
For the first part we easily know the total traveled length which is:
d = 50.2 m + 50.2 m = 100.4 m
The time can be found dividing the distance by the velocity:
t1 = 50.2 m / 2.21 m/s = 22.7149 s
t2 = 50.2 m / 4.11 m/s = 12.2141 s
t = t1 +t2 = 34.9290 s
Therefore, the average velocity is:
v = d/t =2.87 m/s
b)
Here we can easily know the total time:
t = 1 min + 1.16 min = 129.6 s
Now the distance wil be found multiplying each velocity by the time it has travelled:
d1 = 2.21 m/s * 60 s = 132.6 m
d2 = 4.11 m/s *(1.16 * 60 s) = 286.056 m
d = 418.656 m
Therefore, the average velocity is:
v = d/t =3.23 m/s
Force=mass x acceleration
f= 0.5 x40
f=20N
Explanation:
Given that,
Length of gold wire, l = 4 m
Voltage of battery, V = 1.5 V
Current, I = 4 mA
The resistivity of gold, 
Resistance in terms of resistivity is given by :

Also, V = IR
So,

A is area of wire,
, r is radius, r = d/2 (diameter=d)

Out of four option, near option is (C) 17 μm.
To prepare a 10.0% w/v solution of salt in water in a 100 mL volumetric flask, first you must weigh 10 g of salt because the 10 % 100 is 10 and the given should be 10 % w/v. place the 10 g salt to the volumetric flask then add water up until to mark of the volumetric flask then shake it.
"Radiocarbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon."