Forces MCQ - Practice Questions with Answers

1. Definition- Force is defined as an effect that causes a body to change its state.

• Force on 1 kg mass in the presence of gravity $(g=9.8\mathrm{m}/{\mathrm{s}}^2)$ is 1 kg-f=9.8 N

• Unit of force- 

1. In SI unit- Newton(N)

2. In CGS- 1 dyne (1 newton = 100000 dyne)

• 1 Newton(N) is the force needed to accelerate an object with a mass of 1 kg at a rate of 1 m/s²     (1 N = 1 kg · m/s²)

2.    Types of forces-

a) Contact forces- 

• Contact forces are due to direct physical contact between objects. 

Types of contact forces-

• Tension
• Normal reaction
• Spring force
• Friction

b)   Non-contact forces- 

• These forces act without the necessity of physical contact between objects. 

• They depend on the presence of a “field” in the region of space surrounding the body under consideration. 

Types of non-contact forces-

• Gravitational force
• Electrostatic force
• Magnetic force

c)    Weak forces-

• Vanderwaal force

d)   Nuclear forces

• $\begin{array}{rl}& .F_{\text{nuclear }}>F_{\text{electro }}>F_{\text{gravitation }}\\ & F_e/F_g={10}^{43}\\ & \text{ Therefore, }{F}_e\gg F_g\end{array}$