7/22/2019 -Unit 2 Assignment 01

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Newton’s Laws 

Dalton Nielson

Unit 2 Assignment 1

8. When your car moves along the highway at a constant velocity, the net force on it is zero. Why,then, do you continue running your engine?

If you didn’t continue running your engine you would lose the applied force and then all you have is

friction and that would eventually stop the car.

17. You hold an apple over your head.

a. Identify all the forces acting on the apple and their reaction forces.

When an apple falls there's only a few forces acting on that apple. The basic ones are gravity and

air friction. The reaction force to the earth pulling the apple is the apple pulling the earth up

with the SAME amount of force. The reaction force to air molecules hitting the apple is the

apple exerting an equal and opposite force back on those air molecules.

b. When you drop the apple, identify all the forces acting on it as it falls and the corresponding

reaction forces.

The forces that are acting on the apple as it falls would be gravity force and air resistance.

25. Suppose two carts, one twice as massive as the other, fly apart when the compressed spring that

 joins them is released. How fast does the heavier cart roll compared with the lighter cart?

The heavier cart is moving at half the speed than the lighter cart.

33. Why is it that a cat that falls from the top of a 50 story building will hit a safety net below no faster

than if it fell from the twentieth story?

It is assumed that the cat reaches terminal velocity from the 20th

 floor before hitting the net, so

therefore it doesn’t matter how high the cat falls it will always reach terminal velocity at the 20th

 story.

43. A stone is shown at rest on the ground.

a. The vector shows the weight of the stone. Complete the vector diagram showing another

vector that results in zero net force on the stone.

Rock 

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b. What is the conventional name of the vector you have drawn?

Normal force

12. Forces of 3N and 4N act at right angles on a block of mass 5kg. Show that the resulting

acceleration is 1 m/s2.

Define Angular speed (rotational speed) and tangential speed, and specify units for each.

The definition of Angular speed is the change of direction per unit time, as of a target on a radar screen,

without regard to the direction of the rotation axis; in other words, the magnitude of the angular

velocity vector. Which is also known as angular rate.

5k3 N

5 N

4 N

A2 + B = C2

A2 + B

2 = C

2

A2 + B

2 = C

32 + 4

2 = 5N

F=ma

5N = 5kg * a

5kg 5kg

5N = 1 m/s2 

5kg