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gtnhenbr [62]
3 years ago
14

a child is riding a bike at a speed of 0.6m/s with a total kinetic energy of 12.4J.If the mass of the child is 30kg, what is the

mass of the bike?
Physics
2 answers:
Nesterboy [21]3 years ago
8 0
Ek=kinetic energy  (J)
m=mass of object (Kg)
v=speed of object  (m/s)

We have the following formula:

Ek=(1/2)mv²   ⇒ m=2(Ek)/v²

In this case:
m= mass of the child + mass of the bike
m=30 kg + m₁       (m₁=mass of the bike).

We would have to modify our formula like this:

m=2(Ek)/v²
m=30 kg + m₁


30 kg +m₁=2(Ek)/v²
m₁=2(Ek)/v²-30 kg

We have the following data:

v=0.6 m/s
Ek=12.4J
m=30 Kg + m₁

Therefore:

m₁=2(Ek)/v²  - 30 kg
m₁=2(12.4 J)/(0.6 m/s)²  - 30 kg
m₁=24.8 J/(0.36 m²/s²)  -30 kg
m₁=68.89 Kg - 30 kg
m₁=38.89 Kg

Answer: the mass of the bike is 38.89 Kg. 



vova2212 [387]3 years ago
8 0
The mass of the bike is 38.89 Kg. 
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2 years ago
What force is necessary to accelerate a 5.0 kg mass from rest to a final velocity of 10.0 m/s in 5.0 s?
vesna_86 [32]

Answer:

10 N

Explanation:

F = ma = m(Δv/t) = 5.0(10.0 - 0)/5.0 = 10 N

4 0
3 years ago
An object at rest on a flat, horizontal surface explodes into two fragments, one seven times as massive as the other. The heavie
Veronika [31]

Answer:

Explanation:

Given that,

One fragment is 7 times heavier than the other

Let one fragment mass be M

Let this has a velocity v

And the other 7M

And this a velocity V

Initially the fragment is at rest u = 0

Applying conservation of momentum

Momentum is given as p=mv

Initial momentum = final momentum

Po = Pf

(M+7M) × 0 = 7M •V − Mv

0 = 7M•V - Mv

Divide both sides by M

0 = 7V -v

v = 7V

Since friction decelerates the masses to zero speed, we can calculate the NET work on the individual blocks and relate this quantity to the change in kinetic energy of each block

The workdone by the 7M mass is

Distance moved by 7M mass is 6.8m, Then, d =6.8m

W = fr × d

Where fr = µkN

When N=W =mg, where m=7M

N= 7Mg

fr = −µk × 7mg

Then, W(7m) = −7µk•Mg×d

W(7m) = −7µk•Mg×6.8

W(7m) = −47.6 µk•Mg

Then, same procedure,

Let distance move by the small mass be m

Work done by M mass

W(m) = −µk•Mg×d'

Since it is a wordone by friction, that is why we have a negative sign.

Using conservation of energy

Work done by 7M mass is equal to work done by M mass

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Then, M, g and µk cancels out

We are left with

-46.7 = -d

Then, d = 46.7m

7 0
3 years ago
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Bezzdna [24]

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b) Force = mxa

a = 120 N/50 Kg = 2.4 m/s^2

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