Question

an object moving with a velocity of 20m/s increases to velocity of 40m/s in 5sec if the mass of an object is 5kg find out external force acting on it​

Answer 1

Answer:

the required answer is 20 Newton

GIVEN:

• initial velocity, u=20m/s
• final velocity , v=40m/s
• time,t = 5 s
• mass ,m = 5 kg

TO FIND:

external force, f

KEYS:

• f.......force
• m..... mass
• a...... acceleration
• u..... initial velocity
• v.......final velocity
• t......time
• s..... displacement

FORMULAE TO BE USED:

• according to Newton's second law of motion

f= ma

• according to first equation of motion

v = u + at

SOLUTION:

STEP 1: TO FIND ACCELERATION USING FIRST EQUATION OF MOTION

$v = u + at \\ \\ 40 = 20 + a(5) \\ \\ 40 - 20 = 5a \\ \\ 20 = 5a \\ \\ a = 20 \div 5 \\ \\ a = 4m/s^2$

Acceleration, a= 4 m/s^2

STEP2: TO FIND FORCE

$f = ma \\ \\ f = 5 \times 4 \\ \\ f = 20 \: newton$

force is 20 N

RELATED FORMULAE:

FIRST EQUATION OF MOTION

$v = u + at$

SECOND EQUATION OF MOTION

$s = ut + \frac{1}{2} a {t}^{2}$

THIRD EQUATION OF MOTION

${v}^{2} - {u}^{2} = 2as$