Question

6. A: 50 kg man climbing a 'slant length of 5 m<br />along a 30° incline.<br />B : 25 kg man running with 2 m/s speed. <br />C: A force of 5 N acting on an object moving<br />with 5 m/s speed for 5 min.<br />If the energies in A, B and C are Ea, Eb, and<br />Ec respectively, then<br /><br />(a) Ea < Eb <Ec<br />(b) Ea >Eb >Ec<br />(c) Ea < Eb >Ec<br />(d)Eb <Ea<Ec​

Answer 1

Answer:

→ (d)Eb <Ea<Ec​

Explanation:

Ea = mv²/2 = 50x10x5sin30 = 250j

Eb = mv²/2 = 25x4/2 = 50j

Ec  = fvt = 5x25x60 = 7500 j

→ (d)Eb <Ea<Ec​

Answer 2

Answer:

4m/s

Explanation:

MV = m(boy) . v(boy) + m(trolley) . v(trolley) ;

M= net mass in the end i.e boy+ trolley , V= Final velocity of boy + trolley.

Going by this,

MV = 50 * 5 + 20 * 1.5

MV = 280

so, V= 280/M, But M = 50 + 20 =70kg

Hence V = 4m/s