A 1200-kg blue car is traveling at 18.7 M/S. It collides with a stationary red c

Question

A 1200-kg blue car is traveling at 18.7 M/S. It collides with a stationary red car, and the two vehicles lock together. The initial speed of the combined cars is 5.66 m/s. What is the mass of the red car?

2030 kg

2760 kg

2500 kg

1580 kg

10.

A block of mass 15 kg is sliding along the ice at constant speed 4.0 m/s. Just ahead of it is a block of mass 23 kg sliding in the same direction at constant speed 3.6 m/s. When the two blocks collide, the 23-kg block travels at a new speed of 5.2 m/s. What is the new speed of the 15-kg block?

2.1 m/s

0.89 m/s

1.5 m/s

1.0 m/s

5.

A cannon of mass 1200 kg is positioned at the edge of a cliff, where it fires a 100 KG cannonball horizontally. The cannonball's initial speed is 35 m/s What is the recoil speed of the cannon? Assume that friction forces are negligible.

3.5 m/s

1.6 m/s

35 m/s

2.9 m/s

2030 kg

2760 kg

2500 kg

1580 kg

Explanation / Answer

First question -

Applying conservation of momentum -

Mbx18.7 = (Mb+Mr)5.66

=> 1200x18.7 = (1200+Mr)x5.66

=> 1200 + Mr = 3964.66

=> Mr = 2764.66 kg

This is nearest to 2760 kg. So, option 2760 kg is the right answer.

(10) Applying conservation of momentum -

15*4 + 23*3.6 = 15*v + 23*5.2

=> 60+82.8 = 15v + 119.6

=> 15v = 23.2

=> v = 1.55 m/s

So, 1.5 m/s is the correct answer.

(5) 100*35 + 1200*v = 0

=> v = -3500/1200 = -2.92 m/s.

Hence, 2.9 m/s is the correct option.

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