There are 2 defective batteries and 10 good batteries.
a) none of the defective batteries (10C3) = 120
b) one of the defective batteries (10C2)(2C1) = 90
Answer:
Kinetic friction is an inhibitory force that is present when a body or object begins to move. It should be noted that this force is in the opposite direction to the movement of the body that slides with respect to a surface and parallel to that surface.
In addition, this friction varies according to the surface characteristics and the material properties of the bodies that slide in this surface. Being quantified by the coefficient of kinetic friction 
, which is dimensionless.
I): Speed=Distance/Time
=65-30 km/12:30-12:00 hrs
=35 km/00:30hrs
=3500 m/1800 s
=1.94m/s
ii): Average Speed=Total Distance/Total Time
=100000 m/7200 s
=13.88 m/s
iii):No because it has different speeds at
different time intervals
Beginning when the bottom of the object first touches the water,
and as it descends and more and more of it goes under, the
buoyant force on it increases during that time.
As soon as the object is completely underwater, it doesn't matter
how deep under it is, the buoyant force on it remains the same.
Answer:
This is because of the static electricity which is generated in bodies due to friction. Time to time, the door knob gets touched by many people and the charge on it goes on increasing because of increasing friction. When the charge is increased much, after a considerable time, one may get a spark or a mild shock.
