Question

The velocity of a toy of mass 3000 g is increased from 2 m/s to 7 m/s in some time interval. Calculate the gain in kinetic energy of the toy in that time interval.
Please help me friends I have an exam tomorrow

Answer 1

Answer:

37.5J

Explanation:

mass of toy(m) = 3000g or 3kg

change in velocity(v) = 7m/s - 2m/s = 5m/s

therefore, kinetic energy

= ½ * m * v²

= ½ * 3*5²

=37.5 J

therefore, the gain in kinetic energy of the toy in that time interval is 37.5 J

Hope it helps.....thank you

Answer 2

Given :

Mass of the toy = 3000g

Velocity of the toy = 7m/s - 2m/s = 5m/s

To find :

The gain in kinetic energy of the toy in that time interval.

Solution :

Kinetic energy is directly proportional to the mass of the object and to the square of its velocity

• Kinetic energy is a scalar quantity having magnitude
• The SI unit of Kinetic energy is Joule (J).
• The CGS unit of Kinetic energy is erg.

Kinetic energy is related with mass and velocity that is,

$\boxed{ \bf{K.E = \dfrac{1}{2} {mv}^{2} }}$

where,

• m denotes mass in kg
• v denotes velocity in m/s

so, mass of toy = 3000g = 3kg

now, substituting all the given values in the formula,

$\leadsto{ \sf{K.E = \dfrac{1}{2} {mv}^{2} }}$

$\leadsto{ \sf{K.E = \dfrac{1}{2} \times 3 \times {5}^{2} }}$

$\leadsto{ \sf{K.E = 1.5 \times 25}}$

$\leadsto \underline{\boxed{ \purple{ \sf K.E = 37.5 \: J}}} \dag$

thus, kinetic energy of the toy is 37.5 J