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

`2.61m/s^2`

Step-by-step 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=(75)/(9.8)\\m=7.65kg`

From equation (2), we have

`a=(F)/(m)..................(4)`

Hence;

`a=(20)/(7.65)\\a=2.61m/s^2`

Answer 2

2.67 N/kg

Step-by-step 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