Class 11 Work, Energy and Power worksheet

Sample questions

Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.

Section A · multiple choice

1. 1.

   A force of 18 N moves a body 11 m, at 180° to the direction of the force. The work done is:

   1. 99 J
   2. 198 J
   3. −199 J
   4. −198 J

   Answer

   (d) −198 J

   W = Fs cos θ = 18 × 11 × −1

2. 2.

   The kinetic energy of a 19 kg body moving at 19 m/s is:

   1. 3,429.5 J
   2. 6859 J
   3. 180.5 J
   4. 1,714.75 J

   Answer

   (a) 3,429.5 J

   KE = ½mv²

3. 3.

   A machine does 4000 J of work in 7 s. Its power is:

   1. 0.00175 W
   2. 9.52 W
   3. 28000 W
   4. 571.43 W

   Answer

   (d) 571.43 W

   P = W/t

Section B · short answer

1. 4.

   A 12 kg ball falls from rest through a height of 45 m. Find its potential energy at the top and its speed just before it hits the ground (ignore air resistance). (Take g = 10 m/s².)

   Answer

   5,400 J; 30 m/s

   mgh = ½mv²

2. 5.

   A 16 kg box is pulled 15 m across a floor by a horizontal force of 33 N. The coefficient of friction is 0.1. Find the work done by the applied force, by friction, and the gain in kinetic energy. (Take g = 10 m/s².)

   Answer

   495 J; −240 J; 255 J

   work–energy theorem: net work = change in KE

Section C · long answer

1. 6.

   A 4 kg cart moves at 0 m/s at the top of a frictionless track 170 m high and runs down to a point 45 m high. Find (a) its loss of potential energy, (b) its kinetic energy at the lower point, (c) its speed there (2 decimal places if needed). (Take g = 10 m/s².)

   Answer

   (a) 5,000 J; (b) 5,000 J; (c) 50 m/s

   energy is conserved: ½mv₁² + mgh₁ = ½mv₂² + mgh₂

Fresh sheets for your child

In the app, every Work, Energy and Power sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.

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