Question 1041
CBSE Class 11 Physics · Laws of Motion · Newton's laws and free-body diagrams
Explain four observations using Newton's laws:
(a)
a horse-cart cannot accelerate in empty space
(b)
riders lurch forward when a bus stops
(c)
pulling a mower is easier than pushing
(d)
a fielder draws the hands backward while catching.
Solution to Question 1041
Complete workingPrinciple. Acceleration of a system needs external force; inertia preserves motion; friction depends on normal reaction; and force equals momentum change divided by stopping time.
\[(a) \ \text{Horse-cart forces are internal; without ground friction, }F_{ext}=0.\]
\[(b) \ \text{The body retains forward velocity by inertia when the seat slows.}\]
\[(c) \ \text{Pulling has an upward component, reducing }N\text{ and }f=\mu N;\text{ pushing increases both.}\]
\[(d) \ F_{avg}=\Delta p/\Delta t;\text{ increasing catch time reduces force.}\]
Final answer
\[\text{The effects follow respectively from external-force requirement, inertia, friction, and impulse.}\]