Science 7 Semester 2 Exam

What is Newton's third law of motion?

• Object's in motion tend to stay in motion, object's at rest stay at rest

• F = ma

• For every action, there is an equal and opposite reaction

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NGSS.MS-PS2-1

Use the formula to answer the question. Calculate the amount of force a 30 kg textbook exerts on a desk. (let g = 10 m/s²)

• 300 N

• 30 N

• 3 N

• 3000 N

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NGSS.MS-PS2-2

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If car A crashes into car B with 2000 N of force. How much force does Car B crash into car A with? Explain.

Answer explanation

Also 2000 N. Newton's third law states that for every action, there is an equal and opposite reaction. That means if Car B is hit with 2000 N of force, it exerts the same amount of force, but in the opposite direction.

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NGSS.MS-PS2-1

Draw a free body diagram for an egg that is dropped and accelerating towards the ground.

Answer explanation

One small arrow upwards, showing the force of air resistance. One large arrow down showing the force of gravity.

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When the egg hits the ground, how does Newton's third law apply?

Answer explanation

When the egg hits the ground, the force of the egg hitting the ground is equal but opposite to the ground hitting the egg. If the force is too high, the egg will break.

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NGSS.MS-PS2-1

Match the following

• Distance between one crest to the next, or one trough to the next

• Amplitude

• The particles in a transverse wave travel this direction

• Perpendicular

• Distance between the equilibrium and the crest or trough

• Frequency

• Number of wave cycles completed in one second

• Wavelength

• The particles in a longitudinal wave travel this direction

• Parallel

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NGSS.MS-PS4-1

If the frequency of a wave decreases, the period ​ (a)  

If period of a wave in decreases, the frequency of the wave ​ (b)  

• increases
• decreases

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NGSS.HS-PS4-1

Draw two transverse waves, one with high amplitude, and one with low amplitude and one with a high amplitude.

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Does the blue wave, or the red wave have more energy? Explain.

Answer explanation

The red wave has more energy. It has a higher amplitude and amplitude tells us how much energy a wave carries.

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NGSS.MS-PS4-1

Label the longitudinal wave

a

b

c

Rarefaction

Compression

Equilibrium

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