Acceleration Of Block On Horizontal Smooth Surface MCQ - Practice Questions with Answers

• Free Body Diagram (FBD)

In this diagram, the object of interest is isolated from its surroundings and the interactions between the object and the surroundings are represented in terms of forces.

After drawing FBD, Choose the axes and write the equation of motion. This is very helpful while solving questions.

Example- 

1. When the pull is horizontal, and no friction

Balance forces

the body is moving in the x-axis

$\begin{aligned} & \because F_y=0 \\ & R=m g \quad \& \quad F=m a \\ & a=\frac{F}{m}\end{aligned}$

2. Pull Acting at Angle (Upward)

Balancing forces in both X and Y direction,

$\begin{aligned} & R+F \sin \theta=m g \\ & R=m g-F \sin \theta \text { along } Y \text {-axis } \\ & F \cos \theta=m a \text { along } X \text {-axis } \\ & a=\frac{F \cos \theta}{m}\end{aligned}$

3. Push Acting at Angle (Downward)

Balancing forces in both X and Y direction,

$\begin{aligned} & R=m g+F \sin \theta \text { along } Y \text {-axis } \\ & a=\frac{F \cos \theta}{m}_{\text {along } X \text {-axis }}\end{aligned}$