Answer:
125 / 500 = 1/4 of the sample left after 3.0 yrs
1/2 * 1/2 = 1/4 sample has decayed thru 2 half-lives
2 * HL = 3
1 Half-Life = 1.5 yrs
Question is not complete and the missing part is;
A coin of mass 0.0050 kg is placed on a horizontal disk at a distance of 0.14 m from the center. The disk rotates at a constant rate in a counterclockwise direction. The coin does not slip, and the time it takes for the coin to make a complete revolution is 1.5 s.
Answer:
0.828 m/s
Explanation:
Resolving vertically, we have;
Fn and Fg act vertically. Thus,
Fn - Fg = 0 - - - - eq(1)
Resolving horizontally, we have;
Ff = ma - - - - eq(2)
Now, Fn and Fg are both mg and both will cancel out in eq 1.
Leaving us with eq 2.
So, Ff = ma
Now, Frictional force: Ff = μmg where μ is coefficient of friction.
Also, a = v²/r
Where v is linear speed or velocity
Thus,
μmg = mv²/r
m will cancel out,
Thus, μg = v²/r
Making v the subject;
rμg = v²
v = √rμg
Plugging in the relevant values,
v = √0.14 x 0.5 x 9.8
v = √0.686
v = 0.828 m/s
Answer:
I= 27.09 A
Explanation:
Power of electric heater = 1500W= 1.50*10³ W
Power of toaster = 750W = 7.5*10²W
Power of electric grill = 1000W =1*10³ W
Voltage = 120V
By using formula P=VI ie I = 
A) Current used by electric heater I₃ =
I₃ = 12.5 A
B) Current used by toaster I₂ =
I₂ = 6.25 A
C) Current used by electric grill I₃ = 
I₃ = 8.34 A
Current used by all three appliances is
I=I₁+I₂+I₃
I=12.5+6.25+8.34
I= 27.09 A
A negative to a negative charge will make a neutral charge.