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Natasha2012 [34]
3 years ago
8

When exposed to a radioactive source which emits 1.2-MeV gamma-rays, a particular material is found to have a half-value thickne

ss X of 10 cm How thick would a shield made of this material need to be in order to block 75% of the radiation? A. 5 cm B. 20 cm C. 15 cm D. 25 cm E. 10 cm
Physics
1 answer:
iren2701 [21]3 years ago
4 0

Answer:E

Explanation:

It is given that Energy of gamma ray is E=1.2 Mev

Shielding effect can be measured by measuring the fraction of gamma rays blocked by shield. If certain thickness will able to block half the radiation then to block 75% radiation we need to add same amount of thickness in order to block the remaining radiation.

i.e. \frac{E}{2} fraction is blocked by 10 cm thickness

then remaining radiation is \frac{E}{2}

another 10 cm thickness will block the remaining half radiation i.e. \frac{1}{2}\times \frac{E}{2}=\frac{E}{4}

so total 75 % radiation will be blocked

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An object is dropped from a height of 25 meters. At what velocity will it hit the ground?
Vikki [24]
Data:
h=25 m
v₀=0 m/s
g=9,8 m/s²

we use this formula
h=h₀+v₀.t+(1/2).g.t²
25 m=0 m+0 m/s.t+(1/2).(9,8 m/s²).t²
25 m=4,9 m/s².t²
t²=25 m /4,9 m/s²
t²=5,1 s²
t=√(5,1 s²)=2,26 s 

Now, we calculate the última velocity 
v=v₀+gt
v=0 m/s+9,8 m/s².(2,26 s)=22,14 m/s≈22 m/s

solution: c.)  22 m/s


5 0
4 years ago
Define speed.
Vinvika [58]
The answer to the question is choice 2
7 0
3 years ago
A heavy copper ball of mass 2 kg is dropped from a fiftieth-floor apartment window. Another one with mass 1 kg is dropped immedi
STALIN [3.7K]

Answer:

C

Explanation:

Because everything on Earth falls at the same speed, the masses of the balls do not matter. Since the acceleration due to gravity is constant, their speeds will both be increasing at the same rate, and therefore the difference in speeds would remain constant until they hit the ground. Hope this helps!

5 0
3 years ago
A hobby rocket reaches a height of 72.3 m and lands 111 m from the launch point with no air resistance. What was the angle of la
Deffense [45]

Answer:

The angle of launch is 52.49 Degree.

Explanation:

The Range R and Height H of a thrown object is calculated using the formula,

R=V₀² sin(2φ)/g

H=V₀²sin²(φ)/g

From these equations it can be written,

V₀²=R g/ sin(2φ)

V₀²=H g/ sin²(φ)

These values are equal so it can be written by equating these equations,

R g/sin(2φ)=H g/sin²(φ)

tan(φ)= 2H/R

Given H=72.3 m and R=111 m, the angle of launch is,

tan(φ)= 2*72.3/111

φ= 52.49 Degree.

Check out other solutions,

brainly.com/question/1495042

#SPJ10

7 0
2 years ago
A standard steel pipe (D = 3.81 in.; d = 3.24 in.) supports a concentrated load of P = 930 lb. The span length of the cantilever
Maurinko [17]

Answer:

a) τmax = 586.78 P.S.I.

b) σmax = 15942.23 P.S.I

Explanation:

D = 3.81 in

d = 3.24 in

P = 930 lb

L = 3.7 ft = 44.4 in

a) The maximum horizontal shear stress can be obtained as follows

τ = V*Q / (t*I)

where

V = P = 930 lb

Q = (2/3)*(R³- r³) = (1/12)*(D³- d³) = (1/12)*((3.81 in)³- (3.24 in)³)

⇒ Q = 1.7745 in³

t = D - d = 3.81 in - 3.24 in = 0.57 in

I = (π/64)*(D⁴-d⁴) = (π/64)*((3.81 in)⁴- (3.24 in)⁴) = 4.9341 in⁴

then

τ = (930 lb)*(1.7745 in³) / (0.57 in*4.9341 in⁴)

⇒ τmax = 586.78 P.S.I.

b) We can apply the following equation in order to get the maximum tension bending stress in the pipe

σmax = Mmax *y / I

where

Mmax = P*L = 930 lb*44.4 in = 41292 lb-in

y = D/2 = 3.81 in /2 = 1.905 in

I = 4.9341 in⁴

then

σmax = (41292 lb-in)*(1.905 in) / (4.9341 in⁴) = 15942.23 P.S.I

6 0
4 years ago
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