A 20.0 kg block is connected to a 30.0 kg block by a string that passes over a l

Question

A 20.0 kg block is connected to a 30.0 kg block by a string that passes over a light frictionless pulley. The 30.0 kg block is connected to a spring that has negligible mass and a force constant of 220 N/m, as shown in Figure P8.59. The spring is unstretched when the system is as shown in the figure, and the incline is frictionless. The 20.0 kg block is pulled 18.0 cm down the incline (so that the 30.0 kg block is 38.0 cm above the floor) and released from rest. Find the speed of each block when the 30.0 kg block is 20.0 cm above the floor (that is, when the spring is unstretched).

A 20.0 kg block is connected to a 30.0 kg block by a string that passes over a light frictionless pulley. The 30.0 kg block is connected to a spring that has negligible mass and a force constant of 220 N/m, as shown in Figure P8.59. The spring is unstretched when the system is as shown in the figure, and the incline is frictionless. The 20.0 kg block is pulled 18.0 cm down the incline (so that the 30.0 kg block is 38.0 cm above the floor) and released from rest. Find the speed of each block when the 30.0 kg block is 20.0 cm above the floor (that is, when the spring is unstretched). m/s

Explanation / Answer

let

m1 = 20 kg

m2 = 30 kg

k = 220 N/m

apply conservation of energy

increase in kinetic energy = decrease in potential energy

(1/2)*(m1+m2)*v^2 = (1/2)*k*x^2 + m2*g*0.18 - m1*g*0.18*sin(40)

(1/2)*(20+30)*v^2 = (1/2)*220*0.18^2 + 30*9.8*0.18 - 20*9.8*0.18*sin(40)

==> v = 1.16 m/s

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.