Answer:
1) a = -1 m/s²
2) v = 12 m/s
Explanation:
Given,
The initial velocity of the object, u = 15 m/s
The final velocity of the object, v = 10 m/s
The time taken by the object to travel is, t = 5 s
Using the first equation of motion
<em>v = u + at</em>
a = (v - u) / t
Substituting the values
a = (10 - 15) / 5
= -1 m/s²
The negative sign indicates the body is decelerating
The acceleration of the object is, a = -1 m/s²
The speed of the object after 2 seconds
From the above equations of motion
v = 15 + (-1) 2
= 12 m/s
Hence, the speed of the object after 2 seconds is, v = 12 m/s
Answer:
C. Takes heat in, does work, and loses energy heat.
Explanation:
Heat engine is a system makes use of thermal energy (heat) to in order to do mechanical work.
This occurs by converting the heat into mechanical energy. This energy is then used to do work.
The key characteristic of a heat engine is that the substance with which work is done by, goes from a higher temperature to a lower temperature.
Hence, it loses heat as it does work.
The resolution of a microscope is the distance with the shortest measurement between two different points given a specimen with the premise that it can still be seen clearly or distinguished by the one looking through the microscope. It can be calculate from the ratio of the wavelength of the light and twice the numerical aperture or the refractive index of the lens. Most of the microscopes have a numerical aperture ranging from 1.2 to 1.4. Resolution and the numerical aperture are indirectly proportional so that as the aperture increases the resolution would decrease. We calculate as follows:
<span>Resolution = wavelength / ((2) (numerical aperture))
Resolution = 500 nm / (2 ) ( 1.25) = 200 nm = 0.2 um</span>
The answer is aluminum foil is homogeneous
The rate of energy radiated by the man is 3.86 x 
J/s. 
.
The amount of energy radiated by an object majorly depends on the area of its surface and its temperature. The is well explained in the Stefan-Boltzmann's law which states that:
Q(t) = Aeσ
where: Q is the quantity of heat radiated, A is the surface area of the object, e is the emmisivity of the object, σ is the Stefan-Boltzmann constant and T is the temperature of the object.
To determine the rate of energy radiated by the man in the given question;
= Aeσ
But A = 1.7 m², e = 0.4 and σ = 5.67 x J/s.
So that;
= 1.7 * 0.4 * 5.67 x
= 3.8556 x
= 3.86 x J/s.
Thus, the rate of energy radiated by the man is 3.86 x J/s. .
Learn more on energy radiation of objects by visiting: brainly.com/question/12550129
