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Zorluk: OrtaMechanics and Motion

A light training aircraft with a mass of 750 kg750\text{ kg} accelerates from rest along a straight runway under a constant net forward force of 1500 N1{}500\text{ N}. What is the velocity of the aircraft, in meters per second (m/s\text{m/s}), after 8 seconds8\text{ seconds}?

Cevap: 16 m/s

Cevap

16 m/s
According to Newton's second law (F=maF = ma), a net force of 1500 N1{}500\text{ N} applied to a mass of 750 kg750\text{ kg} produces a constant acceleration of a=1500750=2 m/s2a = \frac{1{}500}{750} = 2\text{ m/s}^2. Starting from rest (v0=0v_0 = 0), the velocity after 8 seconds8\text{ seconds} is v=at=2 m/s2×8 s=16 m/sv = at = 2\text{ m/s}^2 \times 8\text{ s} = 16\text{ m/s}.

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1
Calculate the constant acceleration of the aircraft using Newton's second law of motion (Fnet=maF_{\text{net}} = ma).
a=1500 N750 kg=2 m/s2a = \frac{1{}500\text{ N}}{750\text{ kg}} = 2\text{ m/s}^2
Acceleration is directly proportional to net force and inversely proportional to mass.
2
Calculate the final velocity after 8 seconds8\text{ seconds} using the kinematic equation for uniform acceleration (v=v0+atv = v_0 + at).
v=0 m/s+(2 m/s2)(8 s)=16 m/sv = 0\text{ m/s} + (2\text{ m/s}^2)(8\text{ s}) = 16\text{ m/s}
Starting from rest, the final velocity equals the constant acceleration multiplied by elapsed time.

Anahtar Kavram

Newton's Second Law and Uniform Acceleration

Alternatif Yöntem

Apply the impulse-momentum theorem: Impulse=Fnet×Δt=Δp=m×v\text{Impulse} = F_{\text{net}} \times \Delta t = \Delta p = m \times v. Solving for velocity gives v=Fnet×Δtm=1500 N×8 s750 kg=12000750=16 m/sv = \frac{F_{\text{net}} \times \Delta t}{m} = \frac{1{}500\text{ N} \times 8\text{ s}}{750\text{ kg}} = \frac{12{}000}{750} = 16\text{ m/s}.
Tahmini Süre:1m 0s
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