Question

Consider a cart being pulled by a horse with a constant velocity. The horse exerts force ${\overrightarrow{F}}_{C/h}$ on the cart . (The subscript indicates the force on the cart due to the horse.) The first subscript denotes the body on which the force act and the second due to which it acts.
Choose the correct statement (s):

• A. ${\overrightarrow{f}}_{C/g},{\overrightarrow{N}}_{C/g}{,\overrightarrow{N}}_{h/g}$ are external forces on a system consisting of a horse and a cart.
• B. ${\overrightarrow{f}}_{C/g}{\overrightarrow{N}}_{C/g}{\overrightarrow{N}}_{h/g}$
• C. ${\overrightarrow{N}}_{C/g}$ and ${\overrightarrow{F}}_{C/E}$ are action-reaction pairs.
• D. ${\overrightarrow{F}}_{C/h}$ and ${\overrightarrow{F}}_{h/C}$ are action-reaction pairs.

Answer 1

Answer: (A), (B), (D)

The correct options are
A ${\overrightarrow{f}}_{C/g},{\overrightarrow{N}}_{C/g}{,\overrightarrow{N}}_{h/g}$ are external forces on a system consisting of a horse and a cart.
B ${\overrightarrow{f}}_{C/g}{\overrightarrow{N}}_{C/g}{\overrightarrow{N}}_{h/g}$
D ${\overrightarrow{F}}_{C/h}$ and ${\overrightarrow{F}}_{h/C}$ are action-reaction pairs.

(a) For the system of (horse+cart), only $\overrightarrow{F_{c/h}}$ and ${\overrightarrow{F}}_{h/c}$ will be internal forces. All other forces will be external.

(b) As ( horse+cart) system is moving with constant velocity, so net horizontal force on it should be zero.
For this $\overrightarrow{F_{h/g}}+\overrightarrow{f_{c/g}}=0$

(c) $\overrightarrow{N_{C/g}}$ and $\overrightarrow{F_{C/E}}$ cannot be action-reaction pairs, as they act on the same body.

(d) $\overrightarrow{F_{C/h}}$ and $\overrightarrow{f_{h/C}}$ are action-reaction pairs.