Question

please help me friends. please i request

Answer 1

1. 120*5=600
600 watts are used by 5 fans in 1 hour
=600*4=2400
2400 watts are used by 5 fans in 4 hours
As we know,
1 kilowatt=1000 watts
Electicity cosumed by fans= 2.4 kilowatt-hours


2. The initial velocity of the ball, u = 15 m/s
the final velocity of the ball, v = 0
Using the equation of motion:
v2=u2−2gh⇒0=152−2×9.8×h⇒h=22519.6=11.48 m

3. Before Collision:

Car A:
m (mass) = 1500 kg
​u (initial velocity) = 25m/s

Car B:
m (mass) = 1000kg 
​u (initial velocity) = 15m/s
 
After Collision:

According to law of conservation of momentum-
Total momentum before collision = Total momentum after collision

m1u1 + m2u2 = m1v1 + m2v2

1500 X 25 + 1000 X 15 = 1500 X 20 + 1000 X v2

37,500 +  15,000 = 30,000 + 1000 X v2

52,500 = 30,000 + 1000 X v2

52,500 - 30,000 = 1000 X v2

22500 = 1000 X v2

22500 / 1000 = v2

22.5 = v2

Therefore, the velocity after collision = 22.5 m/s

 HOPE IT HELPS MATE !☺