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# M1 impulse question watch

1. for 4b) the right answer is 991n but I don't understand it. I worked out the impulse and worked out r using the equation I=ft to work out r and got 960n. I don't get how the deceleration method works. Thank you.
2. this is what I have done. Thanks.
3. (Original post by coconut64)
for 4b) the right answer is 991n but I don't understand it. I worked out the impulse and worked out r using the equation I=ft to work out r and got 960n. I don't get how the deceleration method works. Thank you.
SInce the peg is being hit vertically, you need to take into account the weight of the combined mass (3.2g).

The resultant force is R - 3.2g upwards which is applied for 0.05 seconds.

Momentum questions are usually horizontal so gravity isn't taken into account which is probably why you missed it.
4. (Original post by notnek)
SInce the peg is being hit vertically, you need to take into account the weight of the combined mass (3.2g).

The resultant force is R - 3.2g upwards which is applied for 0.05 seconds.

Momentum questions are usually horizontal so gravity isn't taken into account which is probably why you missed it.
Oh okay. So if the question ever mentions that the its a vertical movement, weight is always consodered but with horizontal movement, its ignored? Also, do you mind helping me woth thos question ? Thanks. http://www.thestudentroom.co.uk/show....php?t=3966009
5. (Original post by coconut64)
Oh okay. So if the question ever mentions that the its a vertical movement, weight is always consodered but with horizontal movement, its ignored? Also, do you mind helping me woth thos question ? Thanks. http://www.thestudentroom.co.uk/show....php?t=3966009
Weight needs to be considered here because the particle is moving in a vertical direction so the weight will contribute to the acceleration.

If a particle is moving horizontally then the weight will not affect the horizontal movement.

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