F At Amv units: N\'s An impulse on an object results in a change in momentum. I

Question

F At Amv units: N's An impulse on an object results in a change in momentum. I Show your work for Q2 and Q4. 1. State Newton's 3rd Law and describe an actual situation in which it applies. 2. Momentum is defined as p mv (mass x velocity). Both p and v are vectors. Given m-2 kg, and v.-4 m/s, after an impulse v' momentum? (-4m/s), what would be the change in 3. What is an impulse in terms of the physics definition? 4. The momentum change of the object in Question 2 occurred because there was a force on the mass in the negative direction that lasted for 2 seconds. What was the quantity of force?

Explanation / Answer

1)

Newton’s 3rd law of motion states that for every action, there is an equal (in size) and opposite (in direction) reaction force.

Actual situation:

Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. Since forces result from mutual interactions, the air must also be pushing the bird upwards. The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for birds to fly.

2)

Change in momentum = pf - pi

= mvf - mvi

= m (vf - vi)

= 2 (-4 – 4)

= -16 kg-m/s

3)

Impulse is a vector quantity defined as the product of the force acting on a body and the time interval during which the force is exerted.

4)

Impulse = change in momentum = -16

Also,

Impulse = Ft

Thus:

Ft = 16 (taking magnitude only)

=> F = 16/t = 16/2 = 8N

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