Friction is the force you get when you (for example) Rub something with another, it's a force that may generate heat and even some resistance. Another example is rubbing your hands together, they get hot, therefore friction is working, without friction you wouldn't be able to stop moving.
Answer:
c. The coefficient of kinetic friction is less than the coefficient of static friction
Explanation:
When the box finally does break loose. Then the component of the box weight which is parallel to the board weight parallel component, is equal to the
.

For the box to acce;erate thee must be non-zero net force acting on the box parallel to the board. Or we can say,

Therefore the force of kinetic friction must be less than the force of static friction. Thus,

A boiling pot of water (the water travels in a current throughout the pot), a hot air balloon (hot air rises, making the balloon rise) , and cup of a steaming, hot liquid (hot air rises, creating steam) are all situations where convection occurs.
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Answer:
Explanation:
An object is drop from a height, then it is in direction of gravity
g is +ve
When an object drop from a height, the initial velocity is 0,
U=0
Given that h=4.4×10^7m
V=?
g=9.81m/s^2
Then using equation of motion
V^2=U^2+2gh
V^2=0+2×9.81×4.4×10^7
V^2=86.33×10^7m/s
Take square root of both side
V=29381.63m/s
Now to km/s, divide by 1000
Since 1km=1000m
V=29.38km/s
C) During chemical reaction, total mass remains the same.
This is because due to the law of conservation of mass, stating that in a chemical reaction, neither mass will be created nor destroyed. So, the total mass will not change when chemical reactions occur.