What voltage (potential difference)must be applied to a 26 1

Which of the following is not a way in which humans directly impact algal bloom production? a. industrial pollution b. wastewate

iogann1982 [59]

The answer is D. Fishing

6 0

4 years ago

a 45kg boy is holding a 12kg pumpkin while standing on ice skates on a smooth frozen pond. the boy tosses the pumpkin with a hor

irga5000 [103]

Let's split the problem into two parts, and let's solve it by using conservation of momentum.

1) Let's analyze the moment when the boy tosses the pumpkin. Before this moment, the boy is standing with the pumpkin, so with speed v=0 and therefore the total momentum of the system (boy+pumpkin) is zero.
After he tosses the pumpkin, the boy will start to move with speed $v_b$ and the pumpkin starts to move with speed $v_p=2.8 m/s$ . The momentum of the boy is $m_b v_b$ (with $m_b =45 kg$ being the mass of the boy), while the momentum of the pumpkin is $m_p v_p$ (where $m_p=12 kg$ is the mass of the pumpkin). Since the total momentum must be equal to zero (because the total momentum cannot change), then we can write
$m_b v_b + m_p v_p =0$
From which we find
$v_b = - \frac{m_p v_p}{m_b}=- \frac{(12 kg)(2.8 m/s)}{45 kg} =-0.75 m/s$
and this is the speed of the boy, and the negative sign means he's moving in the opposite direction of the pumpkin.

2) Now let's focus on the entire system (boy+pumpkin+girl). Initially, the total momentum of this system is zero, because both the boy (holding the pumpkin) and the girl are still. So, the total momentum after the girl catches the pumpkin must be still zero.
After this moment, the boy has a momentum of $m_b v_b$ , while the girl has momentum $(m_g+m_p)v_g$ where $m_g=37 kg$ is the girl mass $v_g$ is the girl speed. Here we use $m_g+m_p$ because the girl is holding the pumpkin now. Therefore, the conservation of momentum becomes
$m_bv_b + (m_g+m_p)v_g =0$
and so
$v_g = - \frac{m_b v_b}{m_g+m_p} =- \frac{(45 kg)(-0.75 m/s)}{37 kg+12 kg} =0.69 m/s$
and this is the girl's speed, with positive sign so with same direction of the pumpkin initial direction.

6 0

4 years ago

How does the acceleration due to gravity relate to the mass of an object and the distance from Earth?

Irina18 [472]

The object's mass is irrelevant.
The acceleration due to Earth's gravity is inversely proportional to the square of the object's distance from the center of the Earth.

6 0

3 years ago

A fiber-optic cable (n = 1.53) is submerged in water (n = 1.33). Predict whether light will be refracted or whether it will unde

Aleks [24]

Total internal refraction occurs when a ray of light meets the following conditions.
1. light falls from an optically dense material to a less dense material.
2. The angle of incident in the denser media must be greater than the critical angle.

In the case above the fiber-optic is optically denser than water. Since the light is incident to fiber-optic-water interface, then one condition is fulfilled.
Checking the other condition we carry out the calculation below;

n1sinФ1=n2sinФ2
where c ⇒critical angle
1.53 sinc = 1.33 sin 90
sinc =0.86928
c = 60.37°

The angle of incident is (65°-70°) is greater than critical angle.
With certainty, there would be no refraction. Total internal reflection would occur.

7 0

4 years ago

A baseball has an approximate mass of 0.15 kg. If a bat strikes the baseball with a force of 6 N, what is the acceleration of th

Oksanka [162]

Answer:

a = 40 [m/s²]

Explanation:

These kinds of problems can be solved using Newton's second law, which tells us that the sum of forces on a body is equal to the product of mass by acceleration.

∑F = m*a

where:

F = force = 6 [N]

m = mass = 0.15 [kg]

a = acceleration [m/s²]

$a=F/m\\a=6/0.15\\a=40[m/s^{2} ]$

3 0

3 years ago