9.2 Impulse and Collisions

Force integrated over contact time, the impulse-momentum theorem, and why stretching an impact out lowers the peak force felt.

University Physics Volume 1, 9.2 Impulse and Collisions

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6 exercises

9.2 Exercise 1

The U.S. Air Force uses “10gs” (an acceleration equal to $10 \times 9.8 \text{m}/\text{s}^{2}$ ) as the maximum acceleration a human can withstand (but only for several seconds) and survive. How much time must the Enterprise spend accelerating if the humans on board are to experience an average of at most 10gs of acceleration? (Assume the inertial dampeners are offline.)

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9.2 Exercise 2

What if we had assumed the phone did bounce on impact? Would this have increased the force on the iPhone, decreased it, or made no difference?

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9.2 Exercise 3

Is it possible for a small force to produce a larger impulse on a given object than a large force? Explain.

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9.2 Exercise 5

What external force is responsible for changing the momentum of a car moving along a horizontal road?

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9.2 Exercise 11

Water from a fire hose is directed horizontally against a wall at a rate of 50.0 kg/s and a speed of 42.0 m/s. Calculate the force exerted on the wall, assuming the water’s horizontal momentum is reduced to zero.

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9.2 Exercise 13

What is the momentum (as a function of time) of a 5.0-kg particle moving with a velocity $\overset{\rightarrow}{v} \left(t\right) = \left(2.0 \hat{i} + 4.0 t \hat{j}\right) \text{m}/\text{s}$ ? What is the net force acting on this particle?

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