Question

Work done of frictional force from instant ​

Answer 1

• 
  `-100\ J`

Explanation:

1. Find acceleration:

• 
  `m=2\ kg`
• 
  `F=-5\ N`
• 
  `a=(F)/(m)` (Newton's second law)
• 
  `a=(-5)/(2) =-2.5\ (m)/(s^(2))`

2. Find distance traveled:

• 
  `v_0=10\ (m)/(s)`
• 
  `v=0`

• 
  `a=-2.5\ (m)/(s^(2) )`
• 
  `v^2-v_0^2=2ad` (Kinematic equation)
• 
  `-100=-5d`
• 
  `d=20\ m`

3. Find work done by friction:

• 
  `W=Fd` (Work formula when angle between Force and Displacement vectors are 0°)
• 
  `W=-5*20=-100\ J`