For the work-energy theorem, the work needed to stop the bus is equal to its variation of kinetic energy:

where
W is the work
Kf is the final kinetic energy of the bus
Ki is the initial kinetic energy of the bus
Since the bus comes at rest, its final kinetic energy is zero:

, so the work done by the brakes to stop the bus is

And the work done is negative, because the force applied by the brake is in the opposite direction to that of the bus motion.
Answer:
Explanation:A covalent bond is formed when electrons are shared between non-metal atoms, and the positive nuclei are attracted towards the pair of negative bonded electrons. ... Hence, the hydrogen bond is weaker than ionic and covalent bonds. Example: Water molecules are held to each other by intermolecular forces of attraction.
Mass= density x volume
1.3 kg/m^3 x ( 2.5x4x10) m^3
= 130 kg
It would be 12,000 because newton’s third 2nd law states F=ma (force=matter x acceleration) so 30x400 would be your force .
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