Question

A 2.0 kg wood block is launched up a wooden ramp that is inclined at a 35 ∘ angle. The block’s initial speed is 10 m/s . The coefficient of kinetic friction between the block and the ramp is μk = 0.20.

What vertical height does the block reach above its starting point?

Part A

What vertical height does the block reach above its starting point?

Express your answer using two significant figures.

y =

99

  m  

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Part B

What speed does it have when it slides back down to its starting point?

Express your answer using two significant figures.

  

Answer 1

perpendicular to the incline,

N - m g cos35= 0

N = m g cos35

fk = uk N = 0.20 m g cos35 downwar  

along the incline,

Fnet = m a

- fk - m g sin35 = m a

a = - 0.20 g cos35 - g sin35

a = - 7.23 m/s^2

(A) for distance travelled along the incline .

vf^2 - vi^2 = 2 a d

0^2 - 10^2 = 2 (-7.23)(d )

d= 6.92 m

h = d sin35 = 3.97 m ....Ans

(B) while sliding back,
  
fk - m g sin35 = m a

a = 9.8 (0.2 cos35 - sin35) = -4.02 m/s^2

v^2 - 0^2 = 2(-4.02)(-6.92)

v = 7.45 m/s ........Ans