Q1. The volume of 50g of a substance is 20cm3 . If the denstiy of water is 1 g cm3, will the substance float or sink in water ? justify your answer ?

Q2. Show that the energy of a vibrating pendulum is conserved ?

Q3. A ball is dropped from a heigh of 10m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back ?

1.volume of substance= 20 cm^{3}

mass of substance= 50 g

density of substance = mass/volume

=50/20

= 2.5 g/cm^{3}

density of water = 1 g/cm^{3}

2.5 >1

density of substance > density of water

therefore the substance will sink in water.