Each are individual questions in the picture: (5 pts) 4. At point A at the botto

Question

Each are individual questions in the picture: (5 pts) 4. At point A at the bottom ofa rampa box has speed 8.00 m/s. When the box has moved 1.50 m up the ramp to point B its speed is 5.00 m/s. The ramp is inclined at 30 above the horizontal. The box has mass 2.00 kg. How much work did friction do on the box as it moved from A to B? (b) -39.0 J CO-24.3 J 30 (d) -9.6 J (e) none of the above answers (5 pts) 5. A block with mass 5.0 kg is initially at rest on a horizontal frictionless surface. Then a constant horizontal force F is applied to the block. After the force has been applied for 4.0 seconds the speed of the block is 12.0 m/s. What is the magnitude ofthe force? O. a 15.0 N (b) 3.0 N (c) 2.5N (d) 30.0 N e) none of the above answers (5 pts) 6. A rock with mass2.0 kg is at rest on a horizontal frictionless surface. A bullet with mass 0.100 kg is traveling due east with a speed of400 m/s just before it strikes the rock. Just after the collision between the bullet and the rock, the bullet is moving south with a speed of300 m/s. What is the speed of the rock just after the collision with the bullet? (a) 5.0 m/s (b) 15.0 m/s C C 25.0 m/s (d) 59.2 m/s (e) none of the above answers

Explanation / Answer

4)The work done by the frictioanl force will be:

Wf = 1/2 m vb^2 - 1/2 m va^2 - m g h

h = d sin(theta) = 1.5 x sin30 = 0.75

Wf = 1/2 x 2 (5^2 - 8^2) - 2 x 9.8 x 0.75 = -24.3 J

Hence, Wf = -24.3 J

5)a = v/t

a = 12/4 = 3 m/s^2

F = ma = 5 x 3 = 15 N

Hence, F = 15 N

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