LIM - Momentum and Impulse

Momentum and Impulse

Momentum is a quantity that is used to determine what occurs when two objects collide. Momentum, p, is defined as mv. When two objects interact in a closed system, the total momentum of the system is a constant. Newton originally stated his second law of motion such that the sum of the forces applied to an object was the rate of change in momentum. This allows for the solving of force problems when not just the velocity changes but so does the mass. The concept of impulse allows us to relate the variable force to the change in momentum. If a force is constant, then the impulse is equal to LaTeX: \Sigma F\triangle_tΣF△t. Please watch the following presentation that will discuss momentum and impulse. 

Momentum and Impulse Practice

We will now practice solving problems using the concepts you learned in the above presentation. Make sure that you show all your work when you solve your problems. The presentation will give you time to work through the problems, find a solution, and check your work. 

Momentum and Impulse Self-Assessment

Now it's your turn. Complete the self-assessment questions to verify that you can apply the concepts of Momentum and Impulse.

  1. Two blocks of mass M and 4M are placed on a horizontal frictionless surface. Between them a spring of negligible mass is placed that is compressed.   The blocks are released so that the 4M mass moves with a velocity v0 .  
    1. What is the velocity of the block of mass M?
    2. If the value of M is 0.50 kg and v0 is 0.75m/s, how much spring potential energy was stored in the spring?

SOLUTIONS Links to an external site.

  1. A 2 kg ball strikes a wall at an angle of 75o to the surface and bounces back at the same angle.  The magnitude of the velocity is 5 m/s before and after the ball strikes the wall.

Problem 2 Image

    1. What is the change in momentum of the ball?
    2. What is the average force acting on the ball is the collision lasted for 0.25 s?

SOLUTIONS Links to an external site.

  1. A ball is at rest in a ball launcher. The force on the ball varies over time such that LaTeX: F\left(t\right)=2t^2+5t+6F(t)=2t2+5t+6 . The launcher applies a force for 0.25s.
    1. What is the impulse on the ball during this time period?
    2. If the ball is 1.5kg, how fast does it exit the ball launcher?
    3. Assuming the ball was shot horizontally, staring 2 m above the ground, how far would it get before hitting the ground?

SOLUTIONS Links to an external site.

Momentum and Impulse Practice Problems

Download Momentum and Impulse Practice Problems Links to an external site. for more practice. 

Download solutions Links to an external site. to the practice problems. 

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