4. A ball is dropped from height of 45 m. Then distance covered in last 0.6 sec of
its motion will be

1.76 m

Explanation:

Height from which the object is dropped = 45 m

Time (t) remaining for the ball to land = 0.6 s

Height (h) in the remaining =?

The height to which the object falls in the remaining time can be obtained as follow:

Time (t) remaining for the ball to land = 0.6 s

Acceleration due to gravity (g) = 9.8 m/s²

Height (h) in the remaining =?

h = ½gt²

h = ½ × 9.8 × 0.6²

h = 4.9 × 0.36

h = 1.76 m

Thus, the distance travelled in the last 0.6 s is 1.76 m

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000