Question

what is the magnitude o a net force to stop a 100kg object moving at 1 m/s in 5 seconds

Answer 1

What is the magnitude of a net force to stop a 100kg object moving at 1 m/s in 5 seconds?

**Solution.**

$$m = 100kg, v_0 = 1\frac{m}{s}, t = 5s;$$ $$F - ?$$

**Newton's second law:**

$$ma = F;$$ $$a = \frac{F}{m};$$

**Velocity is:**

$$v = v_0 - at;$$

**The object stopped, then**

$$v = 0$$ $$0 = v_0 - at;$$ $$a = \frac{v_0}{t};$$ $$\frac{F}{m} = \frac{v_0}{t};$$ $$F = \frac{m v_0}{t}.$$ $$F = \frac{100 \cdot 1}{5} = 20(N).$$

**Answer:** $F = 20N$.