4. (a) Which row of the table is correct for both force and velocity? | force | velocity | |---------|----------| | A | scalar | scalar | | B | scalar | vector | | C | vector | scalar | | D | vector | vector | (b) Figure 6 shows a satellite orbiting the Earth - Edexcel - GCSE Physics - Question 4 - 2018 - Paper 1

The force that keeps the satellite in orbit around the Earth is called gravitational force or centripetal force.

An arrow should be drawn from the satellite towards the center of the Earth to indicate the direction of the gravitational force acting on the satellite. This arrow should be labeled 'F'.

Red-shift refers to the phenomenon where light from an object moving away from an observer is shifted towards the red end of the spectrum. This indicates that the wavelength of the emitted light is increased while its frequency decreases, suggesting that the object is receding.

Red-shift provides evidence for the Big Bang theory by indicating that galaxies are moving away from us. This observation supports the idea that the universe is expanding, as predicted by the Big Bang theory, where the universe originated from a singular point and has been expanding ever since.

'M' in CMB radiation stands for 'Microwave', referring to Cosmic Microwave Background radiation.

Cosmic background radiation refers to the uniform radiation present throughout the universe, a remnant of the early hot phases after the Big Bang. It is detected as a faint glow in the microwave range.

The presence of CMB radiation supports the Big Bang theory as it is consistent with predictions about the leftover heat from the early universe. The uniformity of this radiation across the cosmos indicates that it originated from a hot, dense state, congruent with Big Bang cosmology.