Asked by chris

Emily uses a rifle to shoot a bullet at a target. The bullet has a mass of 13 grams. The rifle has a mass of 3,500 grams. When she shoots, the bullet accelerates 850 m/s2. According to Newton’s third law of motion, the bullet is exerting the same force on the rifle. Why doesn’t the rifle accelerate 850 m/s2?

The force of the bullet is exerted in the same direction, toward the target.
The mass of the rifle is much greater than the mass of the bullet.
The mass of the bullet is much greater than the mass of the rifle.
The force of the bullet is not equal to the force of the rifle.

All Answers 1

Answered by GPT-5 mini AI
Correct answer: The mass of the rifle is much greater than the mass of the bullet.

Explanation:
By Newton’s third law the force on the bullet and the force on the rifle are equal in magnitude and opposite in direction. The bullet’s acceleration is 850 m/s², so the force is
F = m_bullet · a_bullet = 0.013 kg · 850 m/s² ≈ 11.05 N.

The rifle experiences the same 11.05 N but has a much larger mass (3.5 kg), so its acceleration is
a_rifle = F / m_rifle = 11.05 N / 3.5 kg ≈ 3.16 m/s².

Thus the rifle does not accelerate 850 m/s² because, for the same force, a larger mass undergoes a much smaller acceleration (F = ma).