Question

A body of mass 5 kg moving at a speed of 20 m/s accelerates at 3 m/s2

for 5 seconds. Find

its final kinetic energy. (Ans. 3062.5 Joule)​

Answer 1

$\huge\underline{\overline{\mid{\bold{\blue{\mathcal{ANSWER}}\mid}}}}$

Given:-

• The mass of the block (m)=5.00 kg.

• The acceleration of the block (a) =3 m/s²

• The time for which the block accelerates (t)= 5.00 s.

• Initial speed of the body(u)= 0 m/s

• speed of the moving body= 20m/s

To Find:-

• the kinetic energy of the moving body

For Information:-

* the kinetic energy of an object is the energy that it possesses due to its motion.

$k.e = \frac{1}{2} m {v}^{2}$

where,

m= mass of the body

v= Final velocity of the body

* First equation of motion:-

$v = u + at$

where,

v= final velocity

u= initial velocity

t= time

a= acceleration of the body

Solution:-

For Finding the K.e of the moving body ,we will Use the 1st equation of motion to find the final velocity of the body

$v = u + at$

$= > v =0 + 3 \: m {s}^{ - 12} \times 5 \: s$

$= > v = 15 \: m {s}^{ - 1}$

Now , we will Substitute the Value of Final speed in the formula of kinetic energy

$k.e = \frac{1}{2} \times 5kg \times 15 \: m {s}^{ - 1}$

$= > k.e = \frac{1}{2} \times 15 \: kg \: m {s}^{ - 1}$

$= > k.e = \frac{75}{2} kg \: m \: {s}^{ - 1}$

$= > k.e = 37.5kg \: m \: {s}^{ - 1}$

Answer 2

Answer:

\huge\underline{\overline{\mid{\bold{\blue{\mathcal{ANSWER}}\mid}}}}

∣ANSWER∣

Given:-

The mass of the block (m)=5.00 kg.

The acceleration of the block (a) =3 m/s²

The time for which the block accelerates (t)= 5.00 s.

Initial speed of the body(u)= 0 m/s

speed of the moving body= 20m/s

To Find:-

the kinetic energy of the moving body

For Information:-

* the kinetic energy of an object is the energy that it possesses due to its motion.

k.e = \frac{1}{2} m {v}^{2}k.e=

2

1

mv

2

where,

m= mass of the body

v= Final velocity of the body

* First equation of motion:-

v = u + atv=u+at

where,

v= final velocity

u= initial velocity

t= time

a= acceleration of the body

Solution:-

For Finding the K.e of the moving body ,we will Use the 1st equation of motion to find the final velocity of the body

v = u + atv=u+at

= > v =0 + 3 \: m {s}^{ - 12} \times 5 \: s=>v=0+3ms

−12

×5s

= > v = 15 \: m {s}^{ - 1}=>v=15ms

−1

Now , we will Substitute the Value of Final speed in the formula of kinetic energy

k.e = \frac{1}{2} \times 5kg \times 15 \: m {s}^{ - 1}k.e=

2

1

×5kg×15ms

−1

= > k.e = \frac{1}{2} \times 15 \: kg \: m {s}^{ - 1}=>k.e=

2

1

×15kgms

−1

= > k.e = \frac{75}{2} kg \: m \: {s}^{ - 1}=>k.e=

2

75

kgms

−1

= > k.e = 37.5kg \: m \: {s}^{ - 1}=>k.e=37.5kgms

−1