Question

a moving body of 30 kg has 60 joules of kinetic energy. calculate the speed

Answer 1

Explanation:

K. E=1/2mv^2

60=1/2*30*v^2

60*2/30 =v^2

v^2=4

v=2m/s

Answer 2

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Given:

Mass = 30 kg

Kinetic energy = 60 joule

To find:

Speed = ?

Solution:

$\\ \\ Kinetic \: energy \: = \dfrac{1}{2} mv {}^{2} \\ \\ 60 = \dfrac{1}{2} \times 30 \times v {}^{2} \\ \\ \dfrac{60 \times 2}{30} = v {}^{2}$

$\\ \\ 4 = v {}^{2} \\ \\ taking \: square \: roots \: on \: both \: side \\ \\ v = + 2 \: \\ \\ we \: mostly \: prefer \: positive \: \\ number$

$so \: \: v = 2 \: m /sec$

Required answer:

Therefore, speed of moving body is 2 m/sec

Basic points:

# At highest point, kinetic energy becomes zero as velocity is zero. Kinetic energy is work done to accelerate a body from rest to velocity

# At height, there exist potential energy and at lowest point as height is zero, potential energy is zero

# Solve more such questions to get good hold on it