Anonymous asked in Science & MathematicsPhysics · 2 months ago

Physics velocity?

1. you're playing dodgeball, and you caught a ball thrown at you by another player. The ball has a mass of 0.2 kg. You have a mass of 65 kg. Before catching the ball, you weren’t moving, and after catching the ball, the ball was no longer moving. What was your velocity after catching the ball (the recoil of catching it), if the ball had a starting velocity of..

a. 5 m/s

b. 10 m/s

c. 50 m/s

d. 1,000 m/s

2. a sports car slightly bumps into a van as they both drive in the same direction. The sports car was driving at 20 m/s before the collision, and it weighs 1000 kg. The van was driving at 5 m/s before the collision. After the collision, the sports car ended up rolling at 10 m/s. In this case, what would the velocity of the van have been after the collision, if the van had a mass of...

a. 500 kg

b. 1,000 kg

c. 2,000 kg

d. 5,000 kg


Btw im not asking to solve for all four cases, this is only two multiple choice questions. Im asking which one out of the four options for both im not asking to solve for all 4 per question. in simpler terms i am asking if the answer is A, B, C, or D. for those who misunderstood. Using this to study so would be appreciated.

Update 2:

Oh nevermind i was actually supposed to do all 4 i think that's my fault, ignore the update 

1 Answer

  • NCS
    Lv 7
    2 months ago
    Favorite Answer

    One question per post, please.

    1. Generally, your velocity would still be zero, since you're standing on some surface that provides friction, and that constitutes an "external force." But if somehow you're playing on a frictionless surface, then conservation of momentum yields

    a) 0.2kg * 5m/s = 65kg * V → V = 0.015 m/s

    b) 0.2kg * 10m/s = 65kg * V → V = 0.031 m/s

    c) → V = 0.15 m/s

    d) → V = 3.1 m/s

    2. Same idea, though -- conserve momentum.

    1000kg*20m/s + M*5m/s = 1000kg*10m/s + M*V

    plug in mass and solve for V for each of the four cases.

    If you find this helpful, please select Favorite Answer!

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