First slide

Conservation of mechanical energy

Question

A 0.1 kg block is presses against a horizontal spring fixed at one end to compress the spring through 5cm. The spring constant is $100 N m^{- 1}$ . The ground is 2m below the spring. The velocity with block hits ground is $(g = 10 m s^{- 2})$ _______ $m s^{- 1}$

Moderate

Solution

$\begin{array}{l} W = ΔK . E \\ \frac{1}{2} k x^{2} + m g h = \frac{1}{2} m (v^{2} - 0^{2}) \\ \frac{1}{2} \times 100 \times \frac{25}{100 \times 100} + 0.1 \times 10 \times 2 = \frac{1}{2} \times 0.1 \times v^{2} \\ \frac{1}{8} + 2 = \frac{0.1}{2} \times v^{2} \\ \frac{170}{4} = v^{2} \Rightarrow v = \sqrt{\frac{170}{4}} = 6.519 = 6.52 {ms}^{- 2} \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App