Question

An object that weighs 75n is pulled on a horizontal surface by a horizontal pull of 50 N to the right. The friction force on this object is 30 N to the left. What is the acceleration of the object?

Answer 1

Answer:

$2.61m/s^2$

Explanation:

We first of all find the net force F acting on the object. The frictional force $F_f$ and the pulling force $F_p$ act in opposite directions. Hence the net force is given as follows;

$F=F_p-F_f...............(1)\\Given;\\F_p=50N\\F_f=30N\\Hence;\\F=50-30\\F=20N$

It is this net force that brings about the acceleration of the body. Recall that

$F=ma..............(2)$

where m is the mass of the object and a is the acceleration.

The weight W of the object is given, hence we obtain its mass as follows;

$W=mg..............(3)$

where g is acceleration due to gravity taken as $9.8m/s^2$.

Given;

W = 75N

$75=m*9.8\\m=\frac{75}{9.8}\\m=7.65kg$

From equation (2), we have

$a=\frac{F}{m}..................(4)$

Hence;

$a=\frac{20}{7.65}\\a=2.61m/s^2$

Answer 2

Answer:

2.67 N/kg

Explanation:

We are given that an object that weighing 75 N is pulled on a horizontal surface by a horizontal pull of 50 N to the right with 30 N friction to the left.

We are to find the acceleration of the object.

Mass = 75/10 = 7.5 kg

Acceleration = Net Force / mass

Net force = Horizontal force - Frictional force = 50 - 30 = 20

Acceleration of the object = 20 / 7.5 = 2.67 N/kg