What is the benefit of developing the atomic mass unit as a standard unit of mass?
1 answer:
Answer:
The atomic mass unit is 1/12 of an atom of carbon 12, and is a very small amount to represent in kilograms:
is atomic mass unit.
This is why the benefits of the atomic mass unit is that it makes the representation of atomic masses easier in terms of the simplicity of the numbers that are used to represent the masses. Also using the atomic mass unit it is easier to compare the masses of different atoms, These numbers would be very small and would require negative powers of 10 to represent them, so it is more convenient to use the atomic mass unit.
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Answer:
a) The work done by the applied force is 1500 joules.
b) The kinetic energy of the block after 10 seconds is 1200 joules.
c) The magnitude of the force of friction is 3 newtons and its direction is against motion.
d) 300 joules of energy are lost during motion.
Explanation:
a) Since the object has a constant mass, on which a constant horizontal force is exerted. The work done by the force (), measured in joules, is defined by the following expression:
(1)
Where:
- Force, measured in newtons.
- Distance, measured in meters.
If we know that and
, then the work done by the force exerted on the object is:
The work done by the applied force is 1500 joules.
b) At first we need to calculate the net acceleration of the object (), measured in meters per square second. By assuming a constant acceleration, we use the following kinematic formula:
(2)
Where is the initial velocity of the object, measured in meters per second.
We clear the acceleration within the equation above:
If we know that ,
and
, then the net acceleration experimented by the object is:
By the 2nd Newton's Law, we construct the following equation of equilibrium under the consideration of a friction force acting against the motion of the object:
(3)
Where:
- External force exerted on the object, measured in newtons.
- Kinetic friction force, measured in newtons.
If we know that ,
and
, the kinetic friction force is:
The work done by friction (), measured in joules, is:
(4)
And the net work experimented by the object is:
By the Work-Energy Theorem we understand that change in translational kinetic energy (), measured in joules, is equal to the change in net work. That is:
(5)
If we know that , then the change in translational kinetic energy is:
The kinetic energy of the block after 10 seconds is 1200 joules.
c) The magnitude of the force of friction is 3 newtons and its direction is against motion.
d) The energy lost by the object is equal to the work done by the force of friction. Therefore, 300 joules of energy are lost during motion.
The average force of the water droplets is the force given by the impact
per second of the droplets on the limestone floor.
- The average force exerted on the limestone floor is approximately <u>1.6013 × 10⁻² N</u>
Reasons:
The given parameters are;
Volume of a droplet = 10 ml = 1 × 10⁻⁵ m³
Height from which the water falls, <em>h </em>= 5 meters
Rate at which the water falls = 10 per minute
Required:
The average force exerted on the floor by the water droplets.
Solution:
According to Newton's Second Law of motion, we have;
Force = Rate of change of momentum
Momentum = Mass × Velocity
Mass of a droplet of water = Volume × Density
Density of water = 997 kg/m³
Mass of a droplet = 1 × 10⁻⁵ m³ × 997 kg/m³ = 0.00997 kg
The velocity just before the droplet reaches the ground, v = √(2·g·h)
Where;
g = Acceleration due to gravity ≈ 9.81 m/s²
Which gives;
v = √(2 × 9.81 m/s² × 5 m) ≈ 9.905 m/s
The rate of change in momentum per minute = 1
Therefore;
ΔMomentum = Mass × ΔVelocity
Considering the 10 drops per minute, we have;
ΔMomentum = 10 × 0.0097 kg × 9.905 m/s = 0.960785 kg·m/s
ΔTime = 1 minute = 60 seconds
Therefore;
- The average force exerted on the limestone floor by the droplets of water is
≈ <u>1.6013 × 10⁻² N</u>
Learn more about Newton's Second Law of motion and force exerted water here:
The gravitational force on the woman is A) 500 N
Explanation:
There are two forces acting on the woman during her fall:
- The force of gravity,
, acting downward
- The air resistance,
, acting upward
According to Newton's second law, the net force acting on the woman is equal to the product between the woman's mass and her acceleration:
where m is the mass of the woman and a her acceleration.
The net force can be written as
Also, we know that the woman falls at a constant velocity (5 m/s), this means that her acceleration is zero:
Combining the equations together, we get:
which means that the magnitude of the gravitational force is equal to the magnitude of the air resistance:
Learn more about forces and Newton's second law:
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