Answer:
<em>The magnitude of the force exerted by the person is 100 N</em>
Explanation:
<u>Net Force</u>
According to the second Newton's law, the net force exerted by an external agent on an object of mass m is:
Fn = ma
Where a is the acceleration of the object.
The net force is the sum of all forces exerted over a body. When an object is moved along a rough surface it experiences two horizontal forces and two vertical forces (provided there is no vertical component of the applied force).
The vertical forces are the Normal and the Weight and they are balanced, i.e.: N = W = mg.
The horizontal forces are The applied force (Fa) and the friction force (Fr). They are not balanced because the object is accelerated in that direction. The net force is:
Fn = Fa - Fr
Applying the first equation:
Fa - Fr = ma
Solving for Fa:
Fa = Fr + ma
Substituting the given values m=5 kg, Fr=10 N, 
.
Fa = 10 + 5*18 = 10 + 90 = 100
Fa = 100 N
The magnitude of the force exerted by the person is 100 N
Answer:
<em>If the net force is zero, then the body has an acceleration = 0 m/s²</em>
Explanation:
<em>Force: </em>This is defined as the product of mass of a body and its acceleration. Force is a vector quantity because it can be represented both in magnitude and in direction. The S.I unit of force is<em> Newton (N).</em>
<em>Net Force: </em><em>This is the vector sum of all the the forces acting on a body.</em>
<em>Forces acting in the same direction are added while those acting in opposite directions are subtracted.</em>
<em>Example, if two forces F₁ and F₂ act on a body, in opposite direction, The net force F₃ is express below</em>
<em>F₃ = ma = F₁ - F₂ in the direction of F₁</em>
<em>From the example above, If the net force is zero, then the body has an acceleration = 0 m/s²</em>
Answer:
Explanation:
A thermos helps prevent heat loss when the thermos is holding a hot substance and then helps prevent heat gain when the thermos is holding a cold substance. So a thermos can keep hot things hot and cold things cold.
An elevator has 750,000 J when it is lived 500 meters in the air
Answer: Option D
<u>Explanation:</u>
The expression to find the potential energy completely on the basis of forces that on two objects. It can be written as
Where,
m – mass of object
Acceleration due to gravity = 
h = 500 meters
Force = 1500 Newton
As we know, according to Newton second law of motion, the force can be expressed in terms of mass and gravity (F= ma). So, the potential energy can be calculated as
Hence, an elevator has 750,000 J when it is lived 500 meters in the air.
Impulse in physics is the integral of force, F, with respect with time, t. This value is a vector quantity since force is a vector quantity as well. It can be calculated from the product of force and time. We do as follows:
Impulse = Ft
= m(a)(t)
= m(v/t)t
= 0.046 (42/0.0005) (0.0005)
= 1.932 N-s
