Blake stands in a canoe in the middle of a lake. The canoe is stationary. Blake holds an anchor with mass 15 kg, then throws it west with a speed of 8 m/s. Blake has a mass of 115 kg and the canoe has a mass of 20 kg. a. What is the velocity of the canoe after Blake throws the anchor? b. Later that day, a friend in another canoe uses her paddle to push off against Blake's canoe, giving her canoe a forward velocity of 1 m/s. The combined mass of the friend and canoe is 90 kg. What is the resulting velocity of Blake's canoe?
Blake stands in a canoe in the middle of a lake. The canoe is stationary. Blake holds an anchor with mass 15 kg, then throws it west with a speed of 8 m/s. Blake has a mass of 115 kg and the canoe has a mass of 20 kg.
a. What is the velocity of the canoe after Blake throws the anchor?
b. Later that day, a friend in another canoe uses her paddle to push off against Blake's canoe, giving her canoe a forward velocity of 1 m/s. The combined mass of the friend and canoe is 90 kg. What is the resulting velocity of Blake's canoe?
a) Given:-
ma= mass of anchor= 15 kg
va= veloctiy of anchor= 8 m/s
mb= mass of blake= 115 kg
mc= mass of canoe= 20 kg
M= Total mass of blake-canoe system= mb+mc= 115+20= 135 kg
V= veloctiy of the canoe after blake throws the anchor.
Initially the whole system (anchor+canoe+blake) were at rest. (i.e before blake throws the anchor)
Hence intial momentum of the whole system:-
Pi= 0
Final momentum of the whole system:-
Pf= mava + MV = 15×8 + 135V
Using principal of momentum conservation:-
Pi=Pf
=> 0 = 15×8 + 135V
=> V= -0.89 m/s. (Ans)
The -ve sign depicts that the canoe moves in the opposite direction of anchor (i.e east)
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