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

Q. 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

-3 N

-30 N

3 N

30 N

From the first equation of motion $v = u + a t$ 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 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

-3 N

-30 N

3 N

30 N

From the first equation of motion v=u+at 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

From the first equation of motion $v = u + a t$ 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 $F = ma = 10 \times (- 3) = - 30 N$