Question

Help please

Answer 1

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 and the canoe have a combined mass of 135 kg.

a. The system is defined as Blake, the canoe, and the anchor. What is the total momentum of the system before he throws the anchor?




b. What is the total momentum of the system after he throws the anchor?








c. What is the velocity of the canoe after he throws the anchor?

Answer 2

a) before he throws the anchor nothing is moving so what's the total momentum?

Answer 3

zero

Answer 4

Y

Answer 5

okay so for a it would be zero

Answer 6

for b it would be p=mv
so
p=135*8
p=1080 kg m/s

Answer 7

a. The system is defined as Blake, the canoe, and the anchor. What is the **total momentum of the system** before he throws the anchor?

ZERO


b. What is the **total momentum of the system** after he throws the anchor?

ZERO - No external force has acted on the system to change that

Answer 8

okay so zero for both a and b

Answer 9

yes, ZERO for both

gonna post a grab of that drawing as it seems to veer to the left when actually displayed



you've now got Total momentum = 0, but the spanner is moving right and the boat and guy to left. Those momenta net off to Zero.

Answer 10

So zero for C as well

Answer 11

Crap, I missed the word West so the drawing is back-to-front. West and East are wrong way round but doesn't really matter.

What you have, from the drawing, is:

\(p_1 + p_2 = 0\)

\(\implies m_1 v_1+ m_2 v_2 = 0\)

Putting in the numbers:

\(135 v_1 + 15 \cdot 8 = 0\)

\(\implies v_1 = -\dfrac{15 \cdot 8}{135} ~ \text{m/s}\)

So, in my crap drawing, Blake and the boat must move to the left in order for the total momentum to remain ZERO.

Voca explains these things way better than I do; so if needed wait for her to come online.

Answer 12

\(v_1 = -0.\dot 8 \text{ m/s}\)

which is a lot smaller than the spanner's velocity because Blake and the boat have a much greater mass