Answer:
11.515 Joule
Explanation:
Volume of aluminium = V = 4.89×10⁻³ m³
Coefficient of volume expansion for aluminum = α = 69×10⁻⁶ /°C
Initial temperature = 19.1°C
Final temperature = 357°C
Pressure of air = 1.01×10⁵ Pa
Change in temperature = ΔT= 357-19.1 = 337.9 °C
Change in volume
ΔV = αVΔT
⇒ΔV = 69×10⁻⁶×4.89×10⁻³×337.9
⇒ΔV = 114010.839×10⁻⁹ m³
Work done
W = PΔV
⇒W = 1.01×10⁵×114010.839×10⁻⁹
⇒W = 11.515 J
∴ Work is done by the expanding aluminum is 11.515 Joule
Answer:
13.98 nC
Explanation:
Capacitance depends upon the area of the plates and their distance of separation.
Radius = r = 0.071 m
separation = d = 0.00126 m
here κ = 1 and ε₀ = 8.85 ₓ 10⁻¹² SI units , for free space.
Area = A = π r² = 0.0158 m²
C = [( 8.85 ₓ 10⁻¹² ) ( 0.0158) ]÷ (0.00126) = 1.11 x 10⁻¹⁰ F
Charge = Q = C V = ( 1.11 x 10⁻¹⁰ F )(126) = 13.98 nC
= 14 nC ( rounded to two significant digits)
How many times did the original sample lose 50% of its radioactivity ?
-- Start with. . . . . . . . . . . . 12 grams.
-- Lose half of it once. . . . . . 6 grams left.
-- Lose half of it again . . . . . 3 grams left.
-- Lose half of it again . . . . . 1.5 grams left.
-- Lose half of it again . . . . . 0.75 gram left.
-- How many times did it lose half ? 4 times.
-- How long does it take to lose half ? 4.5 days.
(That's why it's called the 'half-life'.)
-- How long did it take to lose half, 4 times ?
(4 x 4.5 days) = 18 days .
The answer is C) The water pushed up on the skis
The water reacts to the downward force of the skis by pushing back up against the skis.
