47. An object at moment $t = 0\,\text{s}$ starts moving from rest with constant acceleration. The displacement of this object in the $n$-th second is how many times the displacement in the second $n$ equals the displacement in the second two?
$$\frac{5}{3} \quad (1) \qquad \frac{9}{4} \quad (2) \qquad \frac{3}{2} \quad (3) \qquad 2n \quad (4)$$

A small toy starts moving from the position of rest under a constant acceleration. If it travels a distance of 10 m in $t$ s, the distance travelled by the toy in the next $t$ s will be:
(1) 10 m
(2) 20 m
(3) 30 m
(4) 40 m

The displacement and the increase in the velocity of a moving particle in the time interval of $t$ to $( t + 1 )$ s are 125 m and $50 \mathrm {~m} \mathrm {~s} ^ { - 1 }$, respectively. The distance travelled by the particle in $( t + 2 ) ^ { \text {th} } \mathrm { s }$ is $\_\_\_\_$ m.

A body travels 102.5 m in $\mathrm { n } ^ { \text {th} }$ second and 115.0 m in $( \mathrm { n } + 2 ) ^ { \text {th} }$ second. The acceleration is :
(1) $6.25 \mathrm {~m} / \mathrm { s } ^ { 2 }$
(2) $12.5 \mathrm {~m} / \mathrm { s } ^ { 2 }$
(3) $9 \mathrm {~m} / \mathrm { s } ^ { 2 }$
(4) $5 \mathrm {~m} / \mathrm { s } ^ { 2 }$

A body moves on a frictionless plane starting from rest. If $S_n$ is distance moved between $t = n-1$ and $t = n$ and $S_{n-1}$ is distance moved between $t = n-2$ and $t = n-1$, then the ratio $\frac{S_{n-1}}{S_n}$ is $\left(1 - \frac{2}{x}\right)$ for $n = 10$. The value of $x$ is $\_\_\_\_$.

Q3. A body travels 102.5 m in $\mathrm { n } ^ { \text {th } }$ second and 115.0 m in $( \mathrm { n } + 2 ) ^ { \text {th } }$ second. The acceleration is :
(1) $6.25 \mathrm {~m} / \mathrm { s } ^ { 2 }$
(2) $12.5 \mathrm {~m} / \mathrm { s } ^ { 2 }$
(3) $9 \mathrm {~m} / \mathrm { s } ^ { 2 }$
(4) $5 \mathrm {~m} / \mathrm { s } ^ { 2 }$

Q21. A body moves on a frictionless plane starting from rest. If $S _ { n }$ is distance moved between $t = n - 1$ and $\mathrm { t } = \mathrm { n }$ and $\mathrm { S } _ { \mathrm { n } - 1 }$ is distance moved between $\mathrm { t } = \mathrm { n } - 2$ and $\mathrm { t } = \mathrm { n } - 1$, then the ratio $\frac { \mathrm { S } _ { \mathrm { n } - 1 } } { \mathrm {~S} _ { \mathrm { n } } }$ is $\left( 1 - \frac { 2 } { x } \right)$ for $\mathrm { n } = 10$. The value of $x$ is $\_\_\_\_$ .