Question

part i multiple choice: write the answer that best answers the question in the blank. (1 pt each)

1. which of the laws of motion states, \to every action there is an equal but opposite reaction\?

a. newtons 1st law b. newtons 3rd law
c. newtons 2nd law d. law of conservation of momentum

1. which of the following factors does not affect air resistance?

a. speed b. size
c. spin d. shape

1. which of the following best describes momentum?

a. how much force is needed to change an objects motion
b. how much velocity changes in a given amount of time
c. the tendency of an object to resist a change in motion
d. the balanced forces on a falling object with a constant speed

1. which of the following items has the most inertia?

a. a pencil b. a water bottle
c. your textbook d. the teacher

1. carl and juan are playing catch. carl throws a fastball to juan and it hurts juans hand. why is this the case?

a. greater the acceleration, greater the force b. greater the acceleration, the less the force
c. greater the mass, greater the acceleration d. greater the mass, the less the force

1. a person is on a paddleboard. the person exerts a force on the water with the paddle, causing the water to move. the paddleboard also moves, but in the opposite direction. which statement best explains why this happens?

a. inertia b. newtons 2nd law of motion
c. action and reaction forces d. law of conservation of momentum

1. consider a watermelon that starts from rest and drops straight down from a tall building. air resistance can be ignored. which statement about the watermelons motion is false?

a. the watermelon falls at a constant velocity.
b. the watermelon has a positive acceleration.
c. the watermelons acceleration due to gravity is 9.8 m/s².
d. the watermelon speeds up as it falls.

1. what is the weight (in newtons) of a person with a mass of 95.0 kg?

a. 9.70 n b. 105 n
c. 95.0 n d. 931 n

1. an object has 16 n of force being applied to the right, 16 n of force being applied to the left, and 4 n of force being applied downward. what is the net force on the object?

a. 36 n b. 32 n
c. 4 n downward d. 16 n to the left

1. a 700.0 kg car is driving with an acceleration of 5.0 m/s² down the interstate. what is the force required to accelerate the car?

a. 3,500 n b. 14 n
c. 650 n d. 0.071 n

Explanation:

1. Newton's 3rd Law states that for every action, there is an equal and opposite reaction.
2. Spin does not affect air resistance. Air resistance is affected by speed (higher speed means more resistance), size (larger size, more area to push air, more resistance), and shape (streamlined shapes have less resistance).
3. Momentum is calculated as \(p = mv\) (mass times velocity). The option A is related to force (\(F=ma\)), option B is acceleration (\(a=\frac{\Delta v}{\Delta t}\)), option C is inertia.
4. Inertia is related to mass. The teacher has the largest mass among the options, so the teacher has the most inertia.
5. Using \(F = ma\), when the ball is fast (high - acceleration if we consider the change in velocity upon catching), by \(F=ma\) (assuming mass is non - zero), greater acceleration (in the context of stopping the ball) means greater force.
6. When the person exerts a force on the water (action), the water exerts an equal and opposite force on the paddleboard (reaction) - action and reaction forces (Newton's 3rd Law).
7. When air resistance is ignored, a falling object (like the watermelon) is in free - fall and has an acceleration \(a = g=9.8\ m/s^{2}\), so it speeds up. Constant velocity would imply \(a = 0\), which is false in free - fall.
8. Weight \(W=mg\), where \(m = 95.0\ kg\) and \(g = 9.8\ m/s^{2}\). So \(W=95.0\times9.8=931\ N\).
9. The horizontal forces (16 N right and 16 N left) cancel each other (\(16 - 16=0\)). The only unbalanced force is the 4 N downward.
10. Using \(F = ma\), with \(m = 700.0\ kg\) and \(a = 5.0\ m/s^{2}\), then \(F=700\times5=3500\ N\).

Answer:

1. B. Newton's \(3^{rd}\) Law
2. C. Spin
3. A. How much force is needed to change an object’s motion
4. D. The teacher
5. A. Greater the acceleration, greater the force
6. C. Action and reaction forces
7. A. The watermelon falls at a constant velocity
8. D. \(931\ N\)
9. C. \(4\ N\) downward
10. A. \(3500\ N\)