An object of mass 10 kg moves at a constant speed of 10 m/s. A constant force, that acts for 4 s on the object, gives it a speed 2 m/s in opposite direction. The force acting on the object is

Question

An object of mass 10 kg moves at a constant speed of 10 m/s. A constant force, that acts for 4 s on the object, gives it a speed 2 m/s in opposite direction. The force acting on the object is (A) -3 N (B) -30 N (C) 3 N (D) 30 N

Tardigrade Admin · Accepted Answer

From first equation of motion, v =u+a t v-u =a t, a=(v-u/t) Given: u=10 m/s , v = -2 m/s , t = 4 s a =-(-2-10/4)=-3 m / s 2 So, force acting on the object F= ma=10 ×(-3)=-30 N

Q. An object of mass $10 k g$ moves at a constant speed of $10 m / s$ . A constant force, that acts for $4 s$ on the object, gives it a speed $2 m / s$ in opposite direction. The force acting on the object is

-3 N

-30 N

3 N

30 N

From first equation of motion,
$v = u + a t$
$v - u = a t, a = \frac{v - u}{t}$
Given $: u = 10 m / s, v = - 2 m / s, t = 4 s$
$a = - \frac{- 2 - 10}{4} = - 3 m / s^{2}$
So, force acting on the object
$F = ma = 10 \times (- 3) = - 30 N$

Q. An object of mass 10kg moves at a constant speed of 10m/s. A constant force, that acts for 4s on the object, gives it a speed 2m/s in opposite direction. The force acting on the object is

-3 N

-30 N

3 N

30 N

From first equation of motion, v=u+at v−u=at,a=tv−u​ Given :u=10m/s,v=−2m/s,t=4s a=−4−2−10​=−3m/s2 So, force acting on the object F=ma=10×(−3)=−30N

Q. An object of mass $10 k g$ moves at a constant speed of $10 m / s$ . A constant force, that acts for $4 s$ on the object, gives it a speed $2 m / s$ in opposite direction. The force acting on the object is

From first equation of motion,
$v = u + a t$
$v - u = a t, a = \frac{v - u}{t}$
Given $: u = 10 m / s, v = - 2 m / s, t = 4 s$
$a = - \frac{- 2 - 10}{4} = - 3 m / s^{2}$
So, force acting on the object
$F = ma = 10 \times (- 3) = - 30 N$