The force of friction acts in the opposite direction that the object is moving, so friction slows down the motion of moving objects. Friction also produces unnecessary heat. For example, car engines become hotter because of friction.
Answer:
A) receding from the earth
B) 
Explanation:
- A) receding from the earth
The wavelength went from 434.1nm to 438.6nm, there was an increase in wavelength (also knowecn as redshift due to the doppler efft), this increase is due to the fact that the source that emits the radiation (the distant galaxy) is moving away and therefore the light waves it emits are "stretched", causing us to see a wavelength greater than the original.
- B)
to calculate the relative speed we use the following formula:
where 
is the speed of light: 
is the wavelength emited by the source, and
is the wavelength measured on earth.
we substitute all the values and do the calculations:
the relative speed is:
<u>Answer:</u>
<em>Due to the shortcomings in Piaget’s approach to cognitive development several other theories were put forward.</em>
<u>Explanation:</u>
Jean Piaget is the psychologist that offered explanations about cognitive development in children. There were several shortcomings in his theories and thus alternative theories about cognitive <em>development in children </em>were developed.
<em>Lev Vygotsky</em> proposed another explanation to children’s cognitive development. He strongly emphasized on the influence of culture on <em>children’s cognitive development</em>. He believes that it is through socio-cultural interactions development progresses.
He believed that individualized thoughts begin after these interactions. He take on <em>self-speech </em> was different from Piaget. Vygotsky considered self-speech as a guide to thinking while Piaget thought <em>self-speech to be egocentric. </em>
Answer:
As the skydiver falls to the Earth, she experiences positive acceleration only due to gravity.
Explanation:
As the skydiver falls to the Earth, she experiences friction in the form of air resistance which tries to slow her down and is proportional to the her velocity. So it cannot have a positive acceleration as it acts in opposite direction to slow her down.
Inertia during skydiving is experienced when we open an parachute, the parachute slows down the speed of are descent hence changing our inertia of motion with a velocity.
Only the Earth's, gravitational field has an positive acceleration as it pulls us towards the Earth, hence increasing our velocity.
<span>c. a hot tub full of hot water</span>
