Question

a girl pushes her little brother on his sled with a force of 300N for 750m . How much work is this if the force of friction on acting on sled is 200N

Answer 1

Question

Given:

$$\begin{array}{l} F_{\text{applied}} = 300\ \mathrm{N} \\ d = 750\ \mathrm{m} \\ F_{\text{friction}} = 200\ \mathrm{N} \\ \end{array}$$

Need to find:

$$W - ?$$

Solution:

The friction force and applied force are in opposite direction. So, the net force:

$$F_{\text{net}} = F_{\text{applied}} - F_{\text{friction}} = 300\ \mathrm{N} - 200\ \mathrm{N} = 100\ \mathrm{N}.$$

Therefore, the work done:

$$W = F_{\text{net}} \cdot d = 100\ \mathrm{N} \cdot 750\ \mathrm{m} = 75000\ \mathrm{J}.$$

Answer: 75000 Joules.