explain a metal pin was observed to float on pure water. however the pin sank when a few drops of soap were added to the water
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Answer:
a) 230 Km b) 76.7 km/h c) Please see below
Explanation:
a) If we can neglect the time while the driver accelerated, the movement can be divided in two parts, each of them at a constant speed:
⇒
b) The average x component of velocity, can be calculated applying the definition of average velocity, as follows:
If we choose t₀ = 0 and x₀ = 0, replacing xf and t by the values we have already found, we can find vavg,x as follows:
c) The found value of avg,x is not the same as the arithmetic average of the initial and final values of vx (70 Km/h) due to the time traveled at both velocities was not the same.
If the driver had droven half of the time (1.5 h) at 50 km/h and the other half at 90 km/h, total displacement would have been as follows:
Applying the definition of average velocity once more:
which is the same as the arithmetic average of the initial and final values of vₓ.
The tralational equilibrium condition allows finding that the electric potential is V = 4.8 10¹¹ V
Given parameter
- The mass m = 1.5 g = 1.15 10-3 kg
- The charge on the sphere q = 8.9 10-16 C
- Plate spacing d = 5 cm = 5.00 10-2 m
To find
- The potential difference
Newton's second law states that the force is proportional to the mass and the acceleration of the bodies, in the special case that the acceleration is zero, it establishes the condition for the equilibrium of the bodies
∑ F = 0
Where the bold indicate vector and F is the force
To use this equation we must fix a reference system with respect to which to carry out the decomposition and measurements of the forces; let's fix a system with the horizontal x axis and the vertical y axis, in the attachment I could see a free body diagram.
x- axis
Fe - Tₓ = 0
Fe = Tₓ
y-axis
- W = 0
W =
mg =
The electric force is
Fe = q E = q V / d
let's use trigonometry to decompose the stress
cos 30 = / T
sin 30 = Tₓ / T
= T cos 30
Tₓ = T sin 30
We substitute
q V / d = T sin 30
mg = T cos 30
It's solve the system of equations
= tan 30
V =
It's calculate
V =
V = 4.768 10¹¹ V
In conclusion, using the equilibrium condition, we could find that the electric potential is V = 4.8 10¹¹ V
Learn more about equilibrium condition here:
