The distance covered by car is equal to (assuming it is moving by uniform motion) the product between the car's speed and the time of the car ride, 4 h:

where

is the car's speed

is the duration of the car ride
Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:

The total distance covered is S=255 km, which is the sum of the distances covered by car and train:

which becomes

(1)
we also know that the train speed is 5 km/h greater than the car's speed:

(2)
If we put (2) into (1), we find

and if we solve it, we find


So, the car speed is 20 km/h and the train speed is 25 km/h.
Answer:
a)The approximate radius of the nucleus of this atom is 4.656 fermi.
b) The electrostatic force of repulsion between two protons on opposite sides of the diameter of the nucleus is 2.6527
Explanation:

= Constant for all nuclei
r = Radius of the nucleus
A = Number of nucleons
a) Given atomic number of an element = 25
Atomic mass or nucleon number = 52


The approximate radius of the nucleus of this atom is 4.656 fermi.
b) 
k=
= Coulombs constant
= charges kept at distance 'a' from each other
F = electrostatic force between charges


Force of repulsion between two protons on opposite sides of the diameter



The electrostatic force of repulsion between two protons on opposite sides of the diameter of the nucleus is 2.6527
Answer:
Explanation:
To solve this, we start by using one of the equations of motion. The very first one, in fact
1
V = U + at.
V = 0 + 0.8 * 3.4 = 2.72 m/s.
2.
V = 0 + 0.8 * 4.3 = 3.44 m/s.
3.
d = ½ * 0.8 * 4.3² + 3.44 * 12.9
d = 7.396 + 44.376
d = 51.77 m.
4.
d = 62 - 51.77 = 10.23 m. = Distance
traveled during deceleration.
a = (V² - Vo²) / 2d.
a = (0² - 3.44²) / 20.46
a = -11.8336 / 20.46 = -0.58 m/s²
5.
t = (V - Vo)/a =(0 - 3.44) / -0.58
t = -3.44/-.58 = 5.93 s
= Stop time.
T = 4.3 + 12.9 + 5.93 = 23.13 s. = Total
time the hare was moving.
6.
d = Vo * t + ½ * a * t² = 62 m.
0 + 0.5 * (23.13)² * a = 61
267.5a = 61
a = 61/267.5
a = 0.23 m/s²
Answer:
Letter b is wavelength. Letter a is amplitude.
Explanation:
Let's imagine a simple experiment. Imagine you have a long thick rope which one end is at your hands, and you start an oscillatory motion in it, moving your hand up and down. Then a friend of you take a picture of the rope in motion, looking at the rope laterally. Now let's find the wavelength and amplitude. Amplitude is "The distance from the center of the oscillation of the rope (when the rope was not in motion) to its high or low point", or the vertical displacement, in our experiment. On the other hand, wavelength is "The distance between one high point /low point and the next high point /low point". Take a look at a photo of a wave in your textbook and you will find the answer as well. ; )