Answer:
32cm³
Explanation:
Given parameters:
Density of substance = 2.7g/cm³
Mass of substance = 86.4g
Unknown:
Volume of substance = ?
Solution:
Density is the mass per unit volume of a substance.
Density = 
Since the unknown is volume we solve for it;
mass = density x volume
86.4 = 2.7 x volume
volume = 
= 32cm³
Answer:
U = 1 / r²
Explanation:
In this exercise they do not ask for potential energy giving the expression of force, since these two quantities are related
F = - dU / dr
this derivative is a gradient, that is, a directional derivative, so we must have
dU = - F. dr
the esxresion for strength is
F = B / r³
let's replace
∫ dU = - ∫ B / r³ dr
in this case the force and the displacement are parallel, therefore the scalar product is reduced to the algebraic product
let's evaluate the integrals
U - Uo = -B (- / 2r² + 1 / 2r₀²)
To complete the calculation we must fix the energy at a point, in general the most common choice is to make the potential energy zero (Uo = 0) for when the distance is infinite (r = ∞)
U = B / 2r²
we substitute the value of B = 2
U = 1 / r²
Answer:
The deceleration is 
Explanation:
From the question we are told that
The distance of the car from the crossing is 
The speed is 
The reaction time of the engineer is 
Generally the distance covered during the reaction time is
=> 
=> 
Generally distance of the car from the crossing after the engineer reacts is
=> 
=> 
Generally from kinematic equation
Here v is the final velocity of the car which is 0 m/s
So
=>
Explanation:
Given that,
Force, 
Position of the particle, 
(a) The toque on a particle about the origin is given by :
Taking the cross product of above two vectors, we get the value of torque as :
(b) Let 
is the angle between r and F. The angle between two vectors is given by :
The car will speed up because if the air resistance and friction forces are reacting in the direction opposite to the Applied force, The Net force will still be in the direction of the car's motion and since F=ma a will cause your velocity to increase
