Answer:

Explanation:
Given that:
Absolute temperature of the body, 
- emissivity of the body,

<u>Using Stefan Boltzmann Law of thermal radiation:</u>

where:
(Stefan Boltzmann constant)
Now putting the respective values:


Answer:
Earth would continue moving by uniform motion, with constant velocity, in a straight line
Explanation:
The question can be answered by using Newton's first law of motion, also known as law of inertia, which states that:
"an object keeps its state of rest or of uniform motion in a straight line unless acted upon by an external net force different from zero"
This means that if there are no forces acting on an object, the object stays at rest (if it was not moving previously) or it continues moving with same velocity (if it was already moving) in a straight line.
In this problem, the Earth is initially moving around the Sun, with a certain tangential velocity v. When the Sun disappears, the force of gravity that was keeping the Earth in circular motion disappears too: therefore, there are no more forces acting on the Earth, and so by the 1st law of Newton, the Earth will continue moving with same velocity v in a straight line.
Answer: 140 m
Explanation:
Let's begin by stating clear that motiont is the change of position of a body at a certain time. So, during this motion, the balloon will have a trajectory and a displacement, being both different:
The<u> trajectory</u> is <u>the path followed by the body, the distance it travelled</u> (is a scalar quantity).
The displacement is <u>the distance in a straight line between the initial and final position</u> (is a vector quantity).
So, according to this, the distance the balloon traveled during the first 45 s (its trajectory) is 140 m.
But, if we talk about displacement, we have to draw a straight line between the initial position of the balloon (point 0) to its final position (point 90 m). Being its displacement 95 m.
We know that speed equals distance between time. Therefore to find the distance we have that d = V * t. Substituting the values d = (72 Km / h) * (1h / 3600s) * (4.0 s) = 0.08Km.Therefore during this inattentive period traveled a distance of 0.08Km
Answer:
The decelerating force is 
Solution:
As per the question:
Frontal Area, A = 
Speed of the spaceship, v = 
Mass density of dust, 
Now, to calculate the average decelerating force exerted by the particle:
(1)
Volume, 
Thus substituting the value of volume, V in eqn (1):

where
A = Area
v = velocity
t = time
(2)

From Newton's second law of motion:

Thus differentiating w.r.t time 't':

where
= average decelerating force of the particle
Now, substituting suitable values in the above eqn:
