Answer:
Explanation:
According to the Stefan-Boltzmann law for real radiating bodies:
(1)
Where:
is the energy radiated (in Watts)
is the Stefan-Boltzmann's constant.
is the Surface area of the body
is the effective temperature of the body (its surface absolute temperature) in Kelvin
is the body's emissivity
On the other hand, we are told the human body is roughly approximated to a cylinder of length
and circumference
.
The circumference of a circle is:
where
is the radius. Hence
.
Now we have to input this value for
in the Area of a cylinder formula:


(2)
Substituting (2) in (1):
(3)
Finally:

Answer:
Option 5. 1 and 3
Solution:
The only forces acting on the tennis ball after it has left contact with the racquet and the instant before it touches the ground are the force of gravity in the downward direction and the force by the air exerted on the ball.
The ball after it left follows the path of trajectory and as it moves forward in the horizontal direction the force of the air acts on it.
In the whole projectile motion of the ball, the acceleration due to gravity acts on the ball thus the force of gravity acts on the ball in the downward direction before it hits the ground.
Answer:
-There are no other charges nearby.
Explanation:
-There are no other charges nearby.
If there is no net charge in nearby space then the force on this charge will be ZERO
-If there are other charges nearby, they must all have the same sign as Q.
There there is nearby charge of same sign then it will have repulsion force on Q
-If there are other charges nearby, they must all have the opposite sign of Q.
if there is nearby charge of opposite sign then the force must be attraction force.
-If there are other charges nearby, the total positive charge must equal the total negative charge.
If there exist two type of charges nearby then there may exist either attraction or repulsion force on it
Answer:
D. The friction force increases by 9600 N.
Explanation:
Frictional force is directly proportional to kinetic coefient of friction.
Any lump of osmium is. Iridium and gold are also very close.