Question

An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1 kg moves with a speed of 12ms–1 and the second part of mass 2 kg moves with 8ms–1 speed. If the third part files off with 4ms–1 speed, then its mass is -

Answer 1

Answer:

5 KG

Explanation:

from momentum conservation -p1+p2+p3=0

12i+16j+p3=0

p3=-(12i+16j)

|p3|=(144+265)^1/2

|p3|=√(400)=20kg m/s

now mass of the third part is m3=p3/v3 (v3=4m/s)

so m3 = 20/4 =5kg

Answer 2

Answer:

Explanation:According to law of conservation of linear momentum

P1+pe+p3=0

Here,

p1=1×12=12i

p2=2×8=16j

p3=-(12+16)kgms-1

The magnitude of p3 is

P3=√(12)2+√(16)2

=20kgms-1

m3= p3/v3=20/4=5kgans.