EPChap8-9-10-review

# EPChap8-9-10-review - Chap 8 90 A 1.50 kg snowball is shot...

This preview shows pages 1–2. Sign up to view the full content.

1 Chap. 8 90. A 1.50 kg snowball is shot upward at an angle of 34.0° to the horizontal with an initial speed of 20.0 m/s. (a) What is its initial kinetic energy? (b) By how much does the gravitational potential energy of the snowball–Earth system change as the snowball moves from the launch point to the point of maximum height? (c) What is that maximum height? a) The initial kinetic energy is J 300 2 2 1 = = i i mv K . (b) Know that ( ) ( ) 0 = + i f i f U U K K The final velocity is ( ) J 206 cos cos 2 2 1 2 2 1 = = = = θ i f f i f v m mv K v v Therefore ( ) ( ) J 94 + = = i f i f K K U U (c) Since Δ U = mg Δ y , 2 94 J 6.38 m (1.5 kg)(9.8 m/s ) y Δ= = 95. Two blocks, of masses M = 2.0 kg and 2 M , are connected to a spring of spring constant k = 200 N/m that has one end fixed, as shown in Figure 8-65. The horizontal surface and the pulley are frictionless, and the pulley has negligible mass. The blocks are released from rest with the spring relaxed. (a) What is the combined kinetic energy of the two blocks when the hanging block has fallen 0.090 m? (b) What is the kinetic energy of the hanging block when it has fallen that 0.090 m? (c) What maximum distance does the hanging block fall before momentarily stopping? Hint: a) Conservation of energy will involve the spring energy and KE for M , and gravitational potential energy and KE for 2 M . For c) set both final velocities equal to zero.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 4

EPChap8-9-10-review - Chap 8 90 A 1.50 kg snowball is shot...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online