When the car starts moving it acquires kinetic energy.
For this problem the formula of kinetic energy is:

Where m is the mass of the car = 850kg, and v is the speed of the car.
If we consider insignificant the energy lost by friction with soil and air we can propose the following equation:
Applied energy = Kinetic energy acquired by the car.

The velocity is 5.531 m/s
Refer to the attached figure. Xp may not be between the particles but the reasoning is the same nonetheless.
At xp the electric field is the sum of both electric fields, remember that at a coordinate x for a particle placed at x' we have the electric field of a point charge (all of this on the x-axis of course):

Now At xp we have:


Which is a second order equation, using the quadratic formula to solve for xp would give us:

or

Plug the relevant values to get both answers.
Now, let's comment on which of those answers is the right answer. It happens that
BOTH are correct. This is simply explained by considring the following.
Let's place a possitive test charge on the system This charge feels a repulsive force due to q1 but an attractive force due to q2, if we place the charge somewhere to the left of q2 the attractive force of q2 will cancel the repulsive force of q1, this translates to a zero electric field at this x coordinate. The same could happen if we place the test charge at some point to the right of q1, hence we can have two possible locations in which the electric field is zero. The second image shows two possible locations for xp.
Explanation:
It is given that,
The period of the carrier wave, T = 0.01 s
Let f and
are frequency and the wavelength of the wave respectively. The relationship between the time period and the frequency is given by :


f = 100 Hz
The wavelength of a wave is given by :



So, the frequency and wavelength of the carrier wave are 100 Hz and
respectively. Hence, the correct option is (c).
Initial volume of mercury is
V = 0.1 cm³
The temperature rise is 35 - 5 = 30 ⁰C = 30 ⁰K.
Because the coefficient of volume expansion is 1.8x10⁻⁴ 1/K, the change in volume of the mercury is
ΔV = (1.8x10⁻⁴ 1/K)*(30 ⁰K)(0.1 cm³) = 5.4x10⁻⁴ cm³
The cross sectional area of the tube is
A = 0.012 mm² = (0.012x10⁻² cm²).
Therefore the rise of mercury in the tube is
h = ΔV/A
= (5.4x10⁻⁴ cm³)/(0.012x10⁻² cm²)
= 4.5 cm
Answer: 4.5 cm