A and c
Because it defines the boundaries of the system
Force can alter its direction,slow or stop it you could say it can change its velocity
Question:
A 63.0 kg sprinter starts a race with an acceleration of 4.20m/s square. What is the net external force on him? If the sprinter from the previous problem accelerates at that rate for 20m, and then maintains that velocity for the remainder for the 100-m dash, what will be his time for the race?
Answer:
Time for the race will be t = 9.26 s
Explanation:
Given data:
As the sprinter starts the race so initial velocity = v₁ = 0
Distance = s₁ = 20 m
Acceleration = a = 4.20 ms⁻²
Distance = s₂ = 100 m
We first need to find the final velocity (v₂) of sprinter at the end of the first 20 meters.
Using 3rd equation of motion
(v₂)² - (v₁)² = 2as₁ = 2(4.2)(20)
v₂ = 12.96 ms⁻¹
Time for 20 m distance = t₁ = (v₂ - v ₁)/a
t₁ = 12.96/4.2 = 3.09 s
He ran the rest of the race at this velocity (12.96 m/s). Since has had already covered 20 meters, he has to cover 80 meters more to complete the 100 meter dash. So the time required to cover the 80 meters will be
Time for 100 m distance = t₂ = s₂/v₂
t₂ = 80/12.96 = 6.17 s
Total time = T = t₁ + t₂ = 3.09 + 6.17 = 9.26 s
T = 9.26 s
With the blocking of activation of clotting factors, the rate of conversion of fibrinogen to fibrin will decrease to a huge extent and this will prevent the clot formation.
Option A
<h3><u>Explanation:</u></h3>
The process of stopping of flow of blood through any wound by formation of a clot is known as blood clotting. The clot in blood is formed by conversion of the fibrinogen protein into its polymer form fibrin which forms a meshwork.
The conversion of fibrinogen to fibrin requires a lot of enzymes and factors present which is required one by one, known as the Cascade theory. Total of 13 factors are required, where there are prothrombin, thromboplastin, and different other factors. Inactivation of any of the 13 factors will lead to less conversion of fibrinogen to fibrin, thereby the rate of conversion will highly decrease.
Explanation:
Charges,
The distance between charges, r = 10 cm = 0.1 m
We need to find the magnitude and direction of the electric force. It is given by :
So, the required force between charges is 36 N and it is towards positive charge i.e. +8 μC.