3) A cart is moving on a horizontal track with initial velocity to 0.5 m/s. The

Question

3) A cart is moving on a horizontal track with initial velocity to 0.5 m/s. The m ass of the cart is m = 0.25 kg, and the coefficient of the dynamic friction is = 0.004. a) Calculate the magnitude of the frictional force F b) Calculate the distance D that the cart will travel after the time t1=58. c) Calcultae the time t2 that takes for the cart to stop. 4) A skydiver jumps out of an airplane, then she holds her arms and legs stretched out. After some time, the skydiver's velocity becomes constant v 55 m/s. This is a steady state condition, or "free fall". The mass of the skydiver is m 60 kg. a) Write the Lagrange Equation (LE) for the skydiver in a free fall. b) Calculate the air drag coefficient k c) In a steady state, describe the forces that act upon the skydiver, and calculate the magnitudes of those forces

Explanation / Answer

3) (A) Fu = u N and N = m g

F = u M g = 0.004 x 0.25 x 9.81

F = 9.81 x 10^-3 N ....Ans

(B) a = - F/m = - 0.0392 m/s^2

total distance travelled,

vf^2 - vi^2 =2 a d

0^2 - 0.5^2 = 2(0.0392)(d)

d = 3.19 m

distane travelled in 5 sec

d' = (0.5 x 5) - (0.0392 x 5^2 / 2) = 2.01 m

D = d - d' = 1.18 m .....Ans

(c) vf = vi + a t

0 =0.50 - 0.0392 t

t = 12.8 sec

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