The acceleration of a body is to be doubled from its initial value. By what factor is the acting force to be increased?

Find the ratio of momentum of the two bodies $A$ and $B$ of masses $m$ and $4m$ respectively,moving with the same velocity $v$.

Explain with a suitable example whether or not the force of friction always acts opposite to the direction of motion.

Two forces $F_{1} = 20 \, N$ and $F_{2} = 30 \, N$ are acting on an object in opposite directions as shown in the figure.
$(i)$ What is the net force acting on the object?
$(ii)$ What is the direction of the net force acting on the object?
$(iii)$ If the mass of the body is $10 \, kg$,what will be the acceleration produced in it?

Define $1\, kg$ weight and express it in newton.

State the reason for the following:
$(a)$ All cars are provided with seat belts.
$(b)$ It is dangerous to jump out of a moving bus.
$(c)$ Road accidents at high speeds are much worse than accidents at low speeds.