General Physics I Quiz 10-Due Nov. 16, 2017 Name 1. A 30.0N directed at 25.0° be

Question

General Physics I Quiz 10-Due Nov. 16, 2017 Name 1. A 30.0N directed at 25.0° below the horizontal (see diagram below). The mass of the crate is 10 The surfaces are frictionless. The distance between physics student is pushing a crate across a flat floor from A to B with a constant Force (F) of A and B in the figure is 12.0 m a. Determine the work done on the crate by the student b. Dete c. If the crate was moving at 5m/s at A, determine its speed at B (use energy) 2. The horizontal surface on which the block slides is frictionless. The speed of the block just before it touches the spring is 7.0 m/s. How fast is the block moving at the instant the spring has een compressed by 1 7 cm? (k = 2.5 kN/m)

Explanation / Answer

1a] W = F d cos theta

= 30* 12* cos 25 degree = 326.27 J answer

b] Work done by Normal = 0

So work done by all forces = 326.27 J

c] Work done by all forces = change in KE

326.27 = 0.5 mv^2 - 0.5mu^2

  326.27 = 0.5*10[v^2 - 5^2]

v = sqrt(326.27/5 +5^2)

= 9.5 m/s answer

2] total energy is conserved,

0.5 mu^2 =. 0.5 kx^2 + 0.5mv^2

5*7^2 = 0.5*2500*0.17^2 + 5v^2

v = sqrt((5*7^2 - 0.5*2500*0.17^2)/5)

= 6.463 m/s answer

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