Answer:
During the course of a continuous isometric contraction of given strength, the electrical activity progressively increases. This is due to recruitment of motor units taking place to compensate the decrease in force of contraction occurring in the fatigued muscle fibres.
Explanation:
Force required = F = ?
mass of the car = m = 1200 kg
initial velocity of the car = Vi = 10 m/sec
final velocity of the car = 0
time required to stop the car = t = 20 sec
Using Newton`s 2nd law of motion;
F = ma ………………………(1)
as a = Vf - Vi / t , put this value in equation (1)
F = m ( Vf - Vi /t ) ………………(2)
F = 1200 ( 0 - 10 /20) = - 600 N
here Negative sign shows that external force is acting in opposite direction of the motion to bring it to rest.
we can also calculate this force by using the relation
Rate of change of momentum = net force acting on the object …………(3)
m Vf - m Vi / t = net force acting on the object
m (Vf - Vi / t) = F
1200 ( 0 - 10 /20) = - 600 N = F
so, net force acting on the object =F = - 600 N
Answer:
2.1 As food.
2.2 For clothing and textiles.
2.3 For work and transport.
2.4 In science.
2.5 In medicine.
2.6 In hunting.
2.7 As pets.
2.8 For sport.
