Question

the mass of cyclist together with the bike is 90kg. calculate the increase in kinetic energy if the speed increase from 6.0 km/h to 12 km/h​

Answer 1

Answer:

375 si unit

Explanation

first change your velocity in m/s and apply formula for kinetic energy

and write (final-initial)kinetic energy final=500

and initial is 125 so your answer is 500-125 i.e 375

Answer 2

Solution :-

Mass of cyclist and bike is 90 kg (Together)

• Our initial velocity is 6km/h
• Final velocity is 12km/h.

So we need to find out our increase in Kinetic energy. But let's first change the km/h into m/s by multiplying the given speed by 5/18 m/s.

• Initial velocity (u) = 6 × (5/18) = 5/3 m/s
• Final velocity (v) = 12 × (5/18) = 10/3 m/s

As we know that increase in Kinetic energy is calculated by the formula :

• ∆ K.E. = 1/2 m (v² - u²)

Here,

• m is mass
• v is final velocity
• u is initial velocity

Substituting the values :

>> ∆ K.E. = 1/2 × 90 × [(10/3)² - (5/3)²]

>> ∆ K.E. = 1/2 × 90 × (75/9)

>> ∆ K.E. = 1/2 × 10 × 75

>> ∆ K.E. = 5 × 75

>> ∆ K.E. = 375 J

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