A blue puck with a mass of 4.20 Times 10^-2 kg, sliding with a speed of 0.180 m/

Question

A blue puck with a mass of 4.20 Times 10^-2 kg, sliding with a speed of 0.180 m/s on a frictionless, horizontal air table, makes a perfectly elastic, head-on collision with a red puck with mass to, initially at rest. After the collision, the velocity of the blue puck is 5.0 Times 10^-2 m/s in the same direction as its initial velocity. Find the magnitude of the velocity of the red puck after the collision. Express your answer using two significant figures. Find the direction of the velocity of the red puck after the collision. Find the mass m of the red puck. Express your answer using two significant figures.

Explanation / Answer

A) By law of conservation of momentum

m1v1i+m2v2i=m1v1f+m2v2f -------------(1)

0.0420*0.180+m2*0=0.0420*0.05+m2v2f

m2v2f = 0.00546------------------(2)

By law of conservation of energy

1/2m1v1i2 +1/2m2v2i2 = 1/2m1v1f2 + 1/2m2v2f 2

½*0.0420*0.180^2 +1/2*m2*0^2 = ½*0.0420*0.05^2 + 1/2m2v2f^2

m2v2f^2 = 0.0012558 --------------------(3)

Divide (3) by (2)

v2f = 0.0012558/0.00546 = 0.23 m/s

B) Since we got plus sign to the v2f, v2f is in same direction as v1i and v1f are.

C) Plugging above value In equation (1)

0.0420*0.180+m2*0=0.0420*0.05+m2*0.23

m2= 0.02374kg = 2.4*10^-2 kg

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

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