Answer:
Al2O3 + 3Mg ===》 3MgO + 2Al
Explanation:
Reaction of aluminium oxide with magnesium metal would form magnesium oxide and aluminium metal.
Balancing the stoichiometric equation, the number of atoms at the reactant must be equal to the number of atoms at the product so that law of conservation of matter must hold.
Al203 + 3Mg ====》 3MgO + 2Al
2 aluminium at reactant = 2 aluminium at product
3 oxygen at reactant = 3 oxygen at product
3 magnesium at reactant = 3 magnesium at product.
Part 1)
here Julie is running at speed 5 m/s
So here two balls are thrown at speed 10 m/s towards Julie with respect to her friend standing on the ground.
So here this all speed is real speed of all.
Now as per Anita (let say she is one of her friend standing on ground) the speed of two balls will be same as the given speed as she is observing from ground or stationary frame
As per the frame of Julie
speed of ball 1

towards her in same side
speed of ball 2

towards her from opposite side
Part b)
Now in this case the speed of two balls is given with respect to Julie
so we can say
for ball 1


so in ground frame speed of ball 1 is

Similarly for ball 2


So speed in ground frame of ball 2 is

so its 5 m/s from opposite side
transformer makes use of mutual induction for its operation in which change in magnetic field in one coil due to variation of current , induces voltage in the other coil. so changing magnetic field in the primary coil is very much needed for the transformer. Alternating current is a current which varies with time , hence it is suitable to produce changing magnetic field in the primary coil. on the other hand , the direct current remains constant all the time. hence can not produce a changing magnetic field. so DC current is not useful for transformers.
D. Equal to zero.
Because the forces balance each other.