A body is moving with a velocity of $30~\text{m/s}$ towards the east. After $10~\text s,$ its velocity becomes $40~\text{m/s}$ towards the north. The average acceleration of the body is:
1. $7~\text{m/s}^2$
2. $\sqrt{7}~\text{m/s}^2$
3. $5~\text{m/s}^2$
4. $1~\text{m/s}^2$

A particle moves in space such that:
$x=2t^3+3t+4;~y=t^2+4t-1;~z=2\sin\pi t$
where $x,~y,~z$  are measured in meters and $t$ in seconds. The acceleration of the particle at $t=3$ seconds will be:

A particle is moving along a curve. Select the correct statement.

Which of the following statements is incorrect?