Newtons first law states that if an objects velocity is changing a <u>force</u> must be acting on it.
Explanation:
Newton's first law of motion states that:
"An object at rest (or in uniform motion) will remain at rest (or will continue moving with the same velocity) unless acted upon an unbalanced force"
We can apply this law to a daily life example:
- Take a book at rest on a table: the forces acting on the book are balanced. If we do not apply any other force, we know that the book will remain at rest: this is exactly what is summarized in Newton's first law.
- Take a space probe moving in the interstellar space, very far from any planet or source of gravitational force. Since there are no forces acting on the proble, the probe will continue moving at the same velocity (same speed and same direction) forever, unless stopped by a new force acting on it.
This means that in order to put an object at rest in motion, or to stop an object already in motion, or to change its velocity, an unbalanced force needs to be applied: otherwise, the object will continue having the same velocity (which can be either zero or non-zero), so it will continue having same speed and same direction.
Learn more about Newton laws of motion:
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What is newton's second law of motion?Also give example.
<u>Definition</u>:-
Newton's Second Law of motion states that the rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force. ie., <u>F=ma</u>.
<u>Examples:-</u>
- When you are kicking a ball, you are increasing the speed by applying force to it. Therefore,it accelerates.
- If you use the same force to push a truck and push a car, the car will have more acceleration than the truck.
Derivation:-
For a body of mass 'm' , whose velocity changes from u to v in time t, when Force 'F' is applied.
=>Force∝Change in momentum/Time
=>F∝mv-mu/t
=>F∝m(v-u)/t
=>F∝ma
=>F=kma(a=v-u/t)
=>F=ma(Since k=constant=1)
Answer
-8.67× 10^6 N/C
Explanation:
The Electric Field is defined as force per unit charge.
E = Q/ 4π£r2
Qv= −6.5 μCm3
Qv = Q/ V= Q/ 4/3 πr3
Hence Q = 4/3 πr3 × Qv
Hence E = 4/3 πr3 × Qv / 4π£r2= Qvr/3£
−6.5 μ × 4/ 3×8.854 ×10^-12
-6.5 × 4 × 10^6/3 = -8.67× 10^6 N/C
Note: £ = 8.854×10^-12m/F
is the permittivity of free space
Qv is the charge per unit volume
V is volume and volume
The object is not moving.
My explanation is that say if you sit a ball on the table and it is a smooth surface with no bumps or anything. The ball will sit still since it can’t roll unless you hit it.
Hope this helps!
Answer: 15.87 m
From the equation of motion:
where, 
is the distance traveled, 
is the initial velocity, 
is the acceleration and 
is the time.
The rock free falls under gravity. Initial velocity, 
, 
It took 
for rock to hit the water.
Substitute the values in the given equation:
Hence, the water is 15.87 m below the top level of the well.
