Question

A 10 kg object resting on a horizontal frictionless surface is subjected to two forces: F1 = 30 N directed east and F2 = 50 N directed west. Find (a) its acceleration and (b) displacement after seconds starting from rest. To solve for displacement, use d = ½ at2

Answer 1

Answer:

m = 10 kg

F1 = 30 N

F2 = 50 N

Fnet = 20 N towards west

F = m x a

20 = 10 x a

a = 2 m/s^2

d = 1/2 at2

= 1/2 x 2 t x t (time not given in the qn)

= t x t

Just substitute

Answer 2

Given:

An object of mass 10kg, resting upon a smooth horizontal surface is acted upon by two opposite forces

$F_1=30N$ directed east

$F_2=50N$ directed west

To Find:

• Acceleration of the object.
• Displacement after t seconds.

Solution:

Two opposite forces are acting on the object. The net force on the object

   $F_{NET}=F_1+F_2$

⇒ $F_{NET}=30N+(-50)N$     (Assuming east to be the positive direction)

⇒ $F_{NET}=-20N=20N$ towards west.

So, the acceleration of the object, $a=\frac{F_{NET}}{m}$

                                                            $=2m/s^2$ towards west.

Using the equation of uniformly accelerated motion, displacement of the object after t seconds, $d=\frac{1}{2} at^2$

                                         $=\frac{1}{2} *2*t^2=t^2$

Hence, the acceleration of the object is $2m/s^2$ and the displacement after t seconds is $t^2$.