- #1
nonthesecond
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Mr Green, mass 80 kg, stepped off a boat of mass 35 kg at a speed of 3m/s. how fast did the boat move in the opposite direction?
i have no idea how to work it out?
i have no idea how to work it out?
nonthesecond said:Mr Green, mass 80 kg, stepped off a boat of mass 35 kg at a speed of 3m/s. how fast did the boat move in the opposite direction?
i have no idea how to work it out?
PeterO said:I think you will find that Mr Green and the boat are assumed to be at rest initially, so the total momentum was - and will remain - zero.
PeterO said:I think you will find that Mr Green and the boat are assumed to be at rest initially, so the total momentum was - and will remain - zero.
nonthesecond said:i still don't understand i don't understand what formula to use as well.
PeterO said:If you define the direction Mr Green goes as positive, he will have some positive momentum after he leaves the boat.
To maintain a total of zero, the boat must have an equal sized, but negative momentum - so it will be traveling at an appropriate speed in the negative direction (ie the other way)
nonthesecond said:i think i remeber my teacher saying that it's: 80 + 35= 115
115 x 3 = 375
375/35 = 1.3...m/s
is that correct?
nonthesecond said:i think i remeber my teacher saying that it's: 80 + 35= 115
115 x 3 = 375
375/35 = 1.3...m/s
is that correct?
PeterO said:answer these in order:
What is Mr Green's mass?
What is Mr Green's velocity?
What is Mr Green's momentum?
What is the boat's momentum?
What is the boat's mass?
What is the boat's velocity?
nonthesecond said:you are very kind for helping me.
80kg correct
(+3) - but you didn't answer that question
+240 kg m/s almost correct
105 kg m/s incorrect
35kg correct
no idea for velocity i know formula is f=d/t but you aren't given time or distance.
PeterO said:For that final velocity - think about how you calculated the momentum of Mr Green - and don't forget to use + and - signs correctly.
Velocity is a vector; so can be positive or negative.
EDIT: Hint - answers 3 and 4 add up to zero
PeterO said:For that final velocity - think about how you calculated the momentum of Mr Green - and don't forget to use + and - signs correctly.
Velocity is a vector; so can be positive or negative.
EDIT: Hint - answers 3 and 4 add up to zero
nonthesecond said:is the answer 240/35?
Momentum is a physics concept that describes the quantity of motion of an object. It is the product of an object's mass and its velocity.
Momentum is calculated by multiplying an object's mass (m) by its velocity (v), using the formula p = mv.
The law of conservation of momentum states that in a closed system, the total momentum of all objects before a collision is equal to the total momentum after the collision. This means that momentum is conserved and cannot be created or destroyed.
Momentum affects movement by determining how much force is needed to change an object's motion. Objects with a larger momentum require more force to change their direction or speed compared to objects with a smaller momentum.
Momentum and inertia are closely related concepts. Inertia is the tendency of an object to resist changes in its motion, while momentum is the measure of an object's motion. Objects with a larger momentum have a greater resistance to changes in their motion due to their larger inertia.