On a friction-free horizontal ice rink a sled A of mass glides to the right with an…

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

On a friction-free horizontal ice rink a sled A of mass

4.0\,\text{kg}

glides to the right with an unknown speed

u

. It collides and locks together with a stationary sled B of mass

2.0\,\text{kg}

. The combined sleds move off together with a measured speed of

1.5\,\text{m}\,\text{s}^{-1}

. The speed measurement is subject to an uncertainty of

\pm0.05\,\text{m}\,\text{s}^{-1}

. Answer the following. (i) Derive an expression for the initial speed

u

of sled A in terms of the measured quantities. (ii) Calculate the numerical value of

u

. (iii) Determine the percentage uncertainty in the calculated value of

u

arising from the given uncertainty in the final speed.