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PHYS101: Dynamics and Relativity

Problem Sheet 3

Formative questions (unassessed)

1) A force F = Ax , where A is a constant (20 N/m) and x is displacement in the x direction, acts on an object of mass 500 kg. Under the force, the object starts from rest and moves 5 m in the x direction.

(a) Calculate the work done when the object is moved 5 m. Is this work done by, or against, the force F?

(b) Calculate the final velocity of the object.

(c) How far would the object have travelled if the force acted until it reached a velocity of 10 m/s?

2) A block of mass m1 = 100 g is at rest on a frictionless surface. A force of 5 N is applied to the block for 0.5 s. What velocity does the mass have after the force has acted?

Assessed question for Classwork session

3) Consider an elastic collision between masses m1 and m2. Mass m2 is ten times  lighter than mass m1 . Before the collision m1 travels at velocity u1 = 1 m/s towards m2, which is at rest. After the collision the velocities of the masses are v1 and v2 respectively.

(a) Show that

  [4]

(b) Calculate the values of v1 and v2 , showing all steps in your working.   [10]