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Forces & Newton’s Laws II

Newton’s Second Law

Part A: Constant Force with varying Mass

1. Go to the following website:

https://phet.colorado.edu/sims/html/forces-and-motion-basics/latest/forces-and-motion-basics_en.html

2. Click the “Acceleration” tab at the top of the window.

3. Make sure all of the boxes in the upper right hand corner are checked.

4. Set the Applied Force to 300 N.

5. Place each item listed in Table 2 on the screen.

6. Click Play. Observe and Pause after 2-3 seconds.

7. Record the acceleration a, Sum of the Forces FSum and Friction Force Ff in Table 1

Table 1: Data: Constant Force with varying Mass (2.5 points each)

Item	Mass (kg)	Acceleration a (m/s2)	Sum of Forces FSum (N)	Friction Force Ff (N)
Child	40 kg
Box	50 kg
Man	80 kg
Water pail	100 kg
Refrigerator	200 kg

Observations and Analysis:

Fill in the blank by selecting one of the given options for Question 1. (6 points)

1. At constant force, acceleration varies (directly / inversely) ____________ with mass.

When subjected to the same amount of net external force, a heavier object will experience

(less / greater) ____________ acceleration than a lighter one.

2. What do you observe as the mass increases? (5 points)

Part B: Constant Mass with varying Force

1. Now set the mass to 100 kg. Start the applied force at 300 N.

2. Click Play. Pause after 2-3 seconds. Observe and Record the acceleration a, Sum of the

Forces FSum and Friction Force Ff in Table 2.

3. Slowly increment in intervals of 50 N, pausing after 2-3 seconds to record your results.

Table 2: Data: Constant Mass with varying Force (2.5 points each)

Applied Force (N)	Acceleration a (m/s2)	Friction Force Ff (N)	Sum of Forces FSum (N)
300N
350N
400N
450N
500N

Observations and Analysis:

Fill in the blank by selecting one of the given options for Question 3. (9 points)

3. With constant mass, an objects acceleration varies (directly / inversely)_____________with the net external force applied. This means that the acceleration of an object increases as the force

applied is (decreased / increased)_____________, but its acceleration decreases if the force applied is (decreased / increased)_____________.

4. What do you observe about the external force applied and the object’s acceleration? (5 points)