Friction can be bad by being too strong or too weak.
<span>Sometimes, when it is too strong, it decreases efficiency since some energy is wasted and turns to heat. Friction can also d</span><span>amage equipment/objects like when you slide it on the floor.
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When friction is too weak, like for instance when there is black ice- our center of gravity is displaced too quickly and we can fall. Likewise, if there is a lot of slush on the ground, cars can slip and slide.
Answer:
the third stage was 480 km long
Explanation:
Stage 1:
Time = 1 hours
Speed = 80km
Stage 2:
Time = 2 hours
Speed = 200km
Stage 3:
Time = 4 hours
Let the Distance at the stage 3 be x
Average speed of the train route = 100 km/h
So


Lets find the speed at stage 1
Speed = 
Speed = 
Speed 1= 80 km/hr
The speed at stage 2
Speed = 
Speed = 
Speed 2 = 100 km/hr
The speed at stage 3
Speed = 
Speed = 
Speed 3 = 
we kow that average is ,









x = 480
<span>Primarily C, but depending on what's being discussed, it could be all of the above
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Experiments and fieldwork