Answer:
a) 
b) 
Explanation:
a)
Given:
amount of heat transfer occurred,
initial temperature of car, 
final temperature of car, 
We know that the change in entropy is given by:
(heat is transferred into the system of car)
b)
amount of heat transfer form the system of house, 
initial temperature of house, 
final temperature of house, 
Answer:
A) 
= 1.44 kg m², B) moment of inertia must increase
Explanation:
The moment of inertia is defined by
I = ∫ r² dm
For figures with symmetry it is tabulated, in the case of a cylinder the moment of inertia with respect to a vertical axis is
I = ½ m R²
A very useful theorem is the parallel axis theorem that states that the moment of inertia with respect to another axis parallel to the center of mass is
I = 
+ m D²
Let's apply these equations to our case
The moment of inertia is a scalar quantity, so we can add the moment of inertia of the body and both arms
=
+ 2 
= ½ M R²
The total mass is 64 kg, 1/8 corresponds to the arms and the rest to the body
M = 7/8 m total
M = 7/8 64
M = 56 kg
The mass of the arms is
m’= 1/8 m total
m’= 1/8 64
m’= 8 kg
As it has two arms the mass of each arm is half
m = ½ m ’
m = 4 kg
The arms are very thin, we will approximate them as a particle
= M D²
Let's write the equation
= ½ M R² + 2 (m D²)
Let's calculate
= ½ 56 0.20² + 2 4 0.20²
= 1.12 + 0.32
= 1.44 kg m²
b) if you separate the arms from the body, the distance D increases quadratically, so the moment of inertia must increase
Yes, that's correct. That's a big part of the reason why
the soap floats in water and the sponge sinks in it.
Answer:
a. A baseball after it has been hit - not in free fall
b. A rock that is thrown in the air - not in free fall
c. The moon - free-fall
d. A paper airplane - not in free fall
e. A bird flying - not in free fall
Explanation:
- The free-fall is defined as the falling of an object due to the action of gravity. The object is not experiencing any other force neglecting the air resistance.
- If an object is in free-fall, the direction of its motion is directed towards the center of the earth. It does not have a horizontal component of velocity.
- If the body is under free-fall, but a centripetal force acts on it where it is equal to the gravitational force at that point. The object will have two components of velocity along the tangential line, perpendicular to the radius of the orbit.
a. A baseball after it has been hit - not in free fall according to point 1 & 2.
b. A rock that is thrown in the air - not in free fall according to point 1.
c. The moon - free-fall according to point 3.
d. A paper airplane - not in free fall according to point 1 & 2.
e. A bird flying - not in free fall according to point 1 & 2.
Answer:
471 N
Explanation:
Weight is just another word for the force of gravity.
Weight is a force that acts at all times on all objects near Earth. The Earth pulls on all objects with a force of gravity downward toward the center of the Earth (g-9.81 m/s2)
so we can simply say
weight =mass * gravitaitonal acceleraition
= 48 * 9.81
=470.88 N
= 471 N
