Answer:
K.E = 30,000 J
Explanation:
Given,
The potential energy of the roller coaster car, P.E = 40000 J
The kinetic energy at height h/4, K.E = ?
According to the law of conservation of energy, the total energy of the system is conserved.
At height 'h', the total energy is,
P.E = mgh
K.E = 0
At height 'h/4', the total energy is
P.E + K.E = mgh
P.E = mgh/4
K.E = 1/2 mv²
Therefore,
mgh/4 + 1/2 mv² = mgh
gh/4 + v²/2 = gh
Hence,
v² = 3gh/2
Substituting in the K.E equation
K.E = 1/2 mv²
= 1/2 m (3gh/2)
= 3/4 mgh
= 3/4 x 40000
= 30000 J
Hence, the K.E of the roller coaster car is, K.E = 30000 J
So, this would simplify to about 25 miles per hour
Hope this is what you were looking for!
A)
Q=606 J
<span> W = 418 J
</span><span> From first law of thermodynamics,
</span><span> [ Uf - Ui ] = Q - W
</span><span> [ Uf - Ui ]=606 -418=188 J
</span><span> [ Uf - Ui ]= 188 J
</span><span>
b )
W2 = 1212 J
</span><span> Q2 = ?
</span><span> Ui2=Uf =Ui +188
</span><span> Uf2=Ui
</span> [ Uf2 - Ui2 ]<span>=Ui-(Ui+188)
</span><span> -188 J
</span><span> Q2=W2+(Uf2 -Uf1)
</span><span> Q2 =1212 -188=1024 J
</span><span> Q added in second step (b) so that internal energy is equal to initial internal energy of step (a)=1024 J</span>
