All categories

4 years ago

Two Questions Worth 14 points(Gradpoint)

1 answer:

7 0

1. Pu-239 has a half-life of _____.
 24,100 years
2. Nuclear fusion has not yet been harnessed as an energy source because _____.
a.sufficient pressure cannot be generated

You might be interested in

A ball is attached to a string of length 3 m to make a pendulum. The pendulum is placed at a location that is away from the Eart

Musya8 [376]

1) $0.61 m/s^2$

2) 13.9 s

Explanation:

The acceleration due to gravity is the acceleration that an object in free fall (acted upon the force of gravity only) would have.

It can be calculated using the equation:

$g=\frac{GM}{r^2}$ (1)

where

G is the gravitational constant

$M=5.98\cdot 10^{24} kg$ is the Earth's mass

r is the distance of the object from the Earth's center

The pendulum in the problem is at an altitude of 3 times the radius of the Earth (R), so its distance from the Earth's center is

$r=4R$

where

$R=6.37\cdot 10^6 m$ is the Earth's radius

Therefore, we can calculate the acceleration due to gravity at that height using eq.(1):

$g=\frac{GM}{(4R)^2}=\frac{(6.67\cdot 10^{-11})(5.98\cdot 10^{24})0.}{(4\cdot 6.37\cdot 10^6)^2}=0.61 m/s^2$

The period of a simple pendulum is the time the pendulum takes to complete one oscillation. It is given by the formula

$T=2\pi \sqrt{\frac{L}{g}}$

where

L is the length of the pendulum

g is the acceleration due to gravity at the location of the pendulum

Note that the period of a pendulum does not depend on its mass.

For the pendulum in this problem, we have:

L = 3 m is its length

$g=0.61 m/s^2$ is the acceleration due to gravity (calculated in part 1)

Therefore, the period of the pendulum is:

$T=2\pi \sqrt{\frac{3}{0.61}}=13.9 s$

4 0

3 years ago

a 75 kg man is standing at rest on ice while holding a 4kg ball. if the man throws the ball at a velocity of 3.50 m/s forward, w

AysviL [449]

Answer:

His resulting velocity will be 0.187 m/s backwards.

Explanation:

Given:

Mass of the man is, $M=75\ kg$

Mass of the ball is, $m=4\ kg$

Initial velocity of the man is, $u_m=0\ m/s(rest)$

Initial velocity of the ball is, $u_b=0\ m/s(rest)$

Final velocity of the ball is, $v_b=3.50\ m/s$

Final velocity of the man is, $v_m=?\ m/s$

In order to solve this problem, we apply law of conservation of momentum.

It states that sum of initial momentum is equal to the sum of final momentum.

Momentum is the product of mass and velocity.

Initial momentum = Initial momentum of man and ball

Initial momentum = $Mu_m+mu_b=75\times 0+4\times 0 =0\ Nm$

Final momentum = Final momentum of man and ball

Final momentum = $Mv_m+mv_b=75\times v_m+4\times 3.50 =75v_m+14$

Now, initial momentum = final momentum

$0=75v_m+14\\\\75v_m=-14\\\\v_m=\frac{-14}{75}\\\\v_m=-0.187\ m/s$

The negative sign implies backward motion of the man.

Therefore, his resulting velocity is 0.187 m/s backwards.

3 0

4 years ago

Why does a Ray of light passing through a glass slab not shown dispersion?

Hatshy [7]

Answer:

After refraction at two parallel faces of a glass slab, a ray of light emerges in a direction parallel to the direction of incidence of white light on the slab. As rays of all colours emerge in the same direction (of incidence of white light), hence there is no dispersion, but only lateral displacement.

6 0

3 years ago

Explain the purpose of a three-valve manifold in closed tank level measurement installations.

mamaluj [8]

Answer:

A three valve manifold serves to protect the capsule from being exposed to pressures above the acceptable range and also enables transmitter isolation from the loop of the process

In closed tank level measurement installations the pressure of the gas if presence of gas on top of the liquid will need to be taken account by the use of a reference connection from the level transmitter to the tank top. The valve used in pressure equalization is kept close when the process system is operating normally.

In the event that the transmitter is removed or put into service, it is necessary to ensure that the gas phase which is at the higher pressure is does not over-range the Differential Pressure DP capsule

Explanation:

7 0

3 years ago

When you skid to a stop on your bike, you can significantly heat the small patch of tire that rubs against the road surface. Sup

Xelga [282]

Answer:

E = 169.34 J

Explanation:

First, we need to find the frictional force between the back tire and the road. For that purpose, we use the following formula:

f = μR = μW

f = μmg

where,

f = frictional force = ?

μ = coefficient of friction between tire and road = 0.8

g = 9.8 m/s²

m = mass supported by back tire = (0.5)(90 kg) = 45 kg

Therefore,

f = (0.8)(45 kg)(9.8 m/s²)

f = 352.8 N

Now, for the heat energy we use the formula of work. Because, thermal energy will be equal to work done by frictional force:

E = W = fd

where,

E = Thermal Energy = ?

f = frictional force = 352.8 N

d = displacement = 48 cm = 0.48 m

Therefore,

E = (352.8 N)(0.48 m)

E = 169.34 J

5 0

4 years ago