Answer:


Explanation:
As the disc is unrolling from the thread then at any moment of the time
We have force equation as

also by torque equation we can say



Now we have



Also from above equation the tension force in the string is


Answer: 8.1 x 10^24
Explanation:
I(t) = (0.6 A) e^(-t/6 hr)
I'll leave out units for neatness: I(t) = 0.6e^(-t/6)
If t is in seconds then since 1hr = 3600s: I(t) = 0.6e^(-t/(6 x 3600) ).
For neatness let k = 1/(6x3600) = 4.63x10^-5, then:
I(t) = 0.6e^(-kt)
Providing t is in seconds, total charge Q in coulombs is
Q= ∫ I(t).dt evaluated from t=0 to t=∞.
Q = ∫(0.6e^(-kt)
= (0.6/-k)e^(-kt) evaluated from t=0 to t=∞.
= -(0.6/k)[e^-∞ - e^-0]
= -0.6/k[0 - 1]
= 0.6/k
= 0.6/(4.63x10^-5)
= 12958 C
Since the magnitude of the charge on an electron = 1.6x10⁻¹⁹ C, the number of electrons is 12958/(1.6x10^-19) = 8.1x10^24 to two significant figures.
Summary:
a= 12.0 m/(s^2)
v= 100m/s
t1= 2.0s => s1=?
t2=5.0s => s2=?
t3=10.0s => s3=?
——————
Solution:
• when t1=2.0 s, I have gone:
S1= v*t1 + 1/2*a*(t1^2)
=100.0 *2 + 1/2*12.0*(2.0^2)
=224 (m)
• when t2=5.0s, I have gone
S2=v*t2+ 1/2*a*(t2^2)
= 100*5.0+ 1/2*12.0*(5.0^2)
=650 (m)
•when t3= 10.0s, I have gone:
S3=v*t3+ 1/2*a*(t3^2)
=100*10.0+ 1/2*12*(10.0^2)
=1600 (m)
Answer:
E. The ocean gains more entropy than the iron loses.
Explanation:
When there is a spontaneous process , entropy of the system increases . Here hot iron is losing entropy and ocean is gaining entropy . Net effect will be gain of entropy . That means entropy gained by ocean is more than entropy lost by iron .
Hence option E is correct .
Answer:
0.68 m
Explanation:
α = dL / L1*(dT)
dL = L1(dT) * α
Initial length, L1 = 100
Chang in Length =dL
α linear expansivity ; dL = change in length ; dT = change in temperature ; L1 = initial length
α of iron rod = 1.13 * 10^-5 k
dL = 100(40 - 10) * 1.13 * 10^-5
dL = 100(30) * 1.13 * 10^-5
dL = 3000 * 1.13 * 10^-5
dL = 3390 * 10^-5
dL = 0.0339 m
Error :
Distance measured = 2km = (2 * 1000) = 2000m
[Distance measured / (initial length + change in length)] × change in length
Error = (2000 / (100 + 0.0339)) * 0.0339
Error = (2000 / 100.0339) * 0.0339
Error = 19.993222 * 0.0339
Error = 0.6777702
Error = 0.68 m