#1
for the block of mass 5 kg normal force is given as


friction force is given as


Net force is given as


now we know that



#2
Normal force is given as



now we know that


as object moves with constant velocity

now for coefficient of friction we can use



#3
net force upwards is given as

mass is given as

now as per newton's law we can say



#4
As we know that when block is sliding on rough surface
part a)
net force = applied force - frictional force




part b)
for coefficient of friction we can use


here normal force is given as

now we have

#5
if an object is initially at rest and moves 20 m in 5 s
so we can use kinematics to find out the acceleration



now net force is given as


#6
an object travelling with speed 25 m/s comes to stop in 1.5 s
so here acceleration of object is given as


now the force is gievn as


force between two parallel wire is
f/l = mueo*i1i2/2pir
f/l = 2*10^-7*i1i2/rl
i2 = f*r/2*10^-7*i1
i2 = 342.9 A
It would be positive because if it has more protons than electrons then it's positive. If it had more electrons than protons then it would be negative. if it has the same amount its neutral