Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

A 1.3-kg block is moving to the right at 1.1 m/s just before it strikes and stoc

ID: 1553385 • Letter: A

Question

A 1.3-kg block is moving to the right at 1.1 m/s just before it strikes and stocks to a 1.2 kg block initially at rest. What is the total momentum of the two blocks after the collision? magnitude 1.43 kg middot m/s direction Particle A has a mass of 4.9 g, particle B has a mass of 1.4 g, Particle A is located at the origin, particle B at the point (x, y) = (25 cm, 0). What the location of the center of mass X_cm = cm Y_cm = cm If a particle of mass 5.7 kg is moving east at 10 m/s and a particle of mass 17 kg is moving west at 10 m/s, what is the velocity of the center of mass of the pair? 4.97797 What average is necessary to bring a 50.3-kg sled from rest to a speed of 2.8 m/s in a period of 20.4 s? Assume frictionless ice. 6.9 N in the direction of the sled's motion.

Explanation / Answer

10. Let m1 = 1.3 Kg and v1  = + 1.1 m/s

m2 = 1.2 kg and v2 = 0 ( since it is in rest )

total momentum = m1v1 + m2v2  = ( 1.3 x 1.1 ) + (1.2 x 0)

= 1.43 kgm/s towards right

11. m1 = 4.9 g at ( 0,0 ) m2 = 1.4 g at ( 25,0 )

Xcm  = (m1x1  + m2x2 ) / m1 + m2

= ( 4.9 x 0 + 1.4 x 25 ) / 4.9 +1.4

= 35 / 6.3

= 5.56 cm

Ycm  = (m1y1 + m2y2 ) / m1 + m2

= ( 4.9 x 0 + 1.4 x 0) / 6.3

= 0 cm

12. m1 = 5.7 kg v1 = + 10 m/s

m2 = 17 kg v2  = - 10m/s

velocity of centre of mass Vcm  = (m1v1 + m2v2 ) / m1 + m2

= ( 5.7 x 10 - 17 x 10 ) / 5.7 + 17

=(57 - 170) / 22.7

=-113 / 22.7

= - 4.97797 m/s

negative sign indicates the direction is towards west

13. mass m = 50.3 kg

u = 0 and v = 2.8 m/s t = 20.4 s

force f = m.a = m ( v - u ) / t

= 50.3 ( 2.8 - 0 ) / 20.4

= 140.84 / 20.4

= 6.90 N