Imagine a particle of mass m, constrained to move along the x-axis, subject to some specified force F(x, t). The program of classical mechanics is to deter- mine the position of the particle at any given time: x(t). Once we know that, we can figure out the velocity (\( v=\frac{dx}{dt}\) ), the momentum (p = mv), the kinetic energy ( \( T=\frac{1}{2}mv^2 \) ), or any other dynamical variable of interest. And how do we go about determining x(t)? We apply Newton's second law: F = ma. (For conservative systems the only kind we shall consider, and, fortunately, the only kind that occur at the microscopic level---the force can be expressed as the derivative of a potential energy function, \( F=-\frac{\partial V}{\partial x} \) , and Newton's law reads \( m\frac{d^2x}{dt^2}=-\frac{\partial V}{\partial x} \) .) This, together with appropriate initial conditions (typically the position and velocity at t 0), determines x(t). Quantum mechanics approaches this same problem quite differentl
Bola dengan massa 0,1 kg bergerak dengan kecepatan 20 m/s, dipukul dengan gaya 1.000 N dengan arah berlawanan sehingga lajunya menjadi 40 m/s. Lama pemukul menyentuh bola adalah ....
A. 2 x 10-3 s
B. 3 x 10-3 s
C. 4 x 10-3 s
D. 5 x 10-3 s
E. 6 x 10-3 s
Pembahasan :
Diketahui :
m = 0,1 kg
v1 = -20 m/s
F = 1.000 N
v2 = 40 m/s
Ditanyakan : t ?
&space;\\&space;1000\cdot&space;t&space;&=&space;0,1(40&space;-&space;(-20))&space;\\&space;1000\cdot&space;t&space;&=&space;0,1(60)&space;\\&space;1000\cdot&space;t&space;&=&space;6&space;\\&space;t&space;&=&space;6\times&space;10^{-3}&space;\quad&space;\textrm{s}&space;\end{align*} "\begin{align*} F\cdot t &= m\Delta v \\ F\cdot t &= m(v_2 - v_1) \\ 1000\cdot t &= 0,1(40 - (-20)) \\ 1000\cdot t &= 0,1(60) \\ 1000\cdot t &= 6 \\ t &= 6\times 10^{-3} \quad \textrm{s} \end{align*}")
Jawaban : E
A. 2 x 10-3 s
B. 3 x 10-3 s
C. 4 x 10-3 s
D. 5 x 10-3 s
E. 6 x 10-3 s
Pembahasan :
Diketahui :
m = 0,1 kg
v1 = -20 m/s
F = 1.000 N
v2 = 40 m/s
Ditanyakan : t ?
Jawaban : E
dapet -20 nya dari mana kak??bukannya di soal +20?bukan negative
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