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A 2000-lb car drives from Denver (altitude: 5280 feet) to Los Angeles (sea level). What is its change in potential energy, in BTU? g = 32.174 ft/s² Provide your answer rounded to one decimal place, and make sure to include units. *

2) The velocity of an object increases by 50% (V₂=1.5 V₁). By what factor does the kinetic energy increase? *
1
4
1.5
2.25

Respuesta :

fmorelos

Answer:

1) -13570.3 Btu

2) 2.25

Explanation:

The formula for potential energy is:

[tex]E_p = m*g*h[/tex]

Where m is the mass in slugs, g is the gravity and h is the change in height. Soliving the equation:

[tex]E_p = 2000lb*\frac{1 slug}{32.174 lb} *32.174 \frac{ft}{s^2} *(0ft-5280ft) = -10560000 lbf*ft * \frac{1 Btu}{778.17 lbf*ft} = -13570.3 Btu[/tex]

The car would lose -13570.3 Btu in potential energy.

2) The kinetic energy is given by:

[tex]E_k = \frac{1}{2} mv^2[/tex]

Then:

[tex]\frac{E_k_2}{E_k_1} = \frac{\frac{1}{2}mv_2^2}{\frac{1}{2}mv_1^2}  = \frac{\frac{1}{2}m(1.5v_1)^2}{\frac{1}{2}mv_1^2}=1.5^2\frac{v_1^2}{v_1^2} = 2.25[/tex]