Answer:
6 days.
Explanation:
From radioactivity, The expression for half life is given as,
R/R' = 2⁽ᵃ/ᵇ)................... Equation 1
Where R = original mass of the radioactive substance, R' = Remaining mass of the radioactive substance after decay, a = Total time taken to decay, b = half life.
Given: R = 80 g, R' = 10 g, b = 2 days.
Substitute into equation 1
80/10 = 2⁽ᵃ/²⁾
8 = 2⁽ᵃ/²⁾
2³ = 2⁽ᵃ/²)
Equating the base and solving for a
3 = a/2
a = 2×3
a = 6 days.
Answer:
39.2m/s
Explanation:
The potential energy the book has right before it falls is equal to the kinetic energy in falling.
PE = KE
mgh = (1/2)mv
2gh=v
v=(2)(9.81)(2)
v=39.24m/s
Answer:
The work done by the wind as the boat moves 130 ft is (rounded) W= 31,550 ft-lb.
Explanation:
F= 300 lb < -54º
Fsouth= 300 lb * cos(36º)
Fsouth= 242.7 lb
d= 130 ft
W= F*d
W= 31551 ft-lb
Force=mass x acceleration
f= 0.5 x40
f=20N
Answer:
electron degeneracy pressure...or in other word electro magnetic repulsion
