Answer:
(a) Power= 207.97 kW
(b) Range= 5768.6 meter
Explanation:
Given,
Mass of bullet, 
Kinetic energy imparted, 
Length of rifle barrel, 
(a)
Let the speed of bullet when it leaves the barrel is
.
Kinetic energy, 



Initial speed of bullet, 
The average speed in the barrel,

Time taken by bullet to cross the barrel, 

Power,

(b)
In projectile motion,
Maximum height, 
Range, 
given that, 
then, 
Answer:
20n
Explanation:
60n - 40n = efficiency of pulley system
20n = efficiency of pulley system
Answer:
The weight that will balance the meter stick at 70 cm mark is 35N
Explanation:
Given;
first weight at 15 cm mark, W₁ = 20 N
second weight at 70 cm mark, W₂ = ?
A sketch of the question in diagram form;
The center of gravity of the meter stick is 50 cm
15cm 50cm 70cm
0---------------------------------------Δ------------------------------------------100cm
↓ ↓
20N W₂
<------------------>|<--------------->
35cm 20cm
Take moment about the pivot;
Clockwise moment = anticlockwise moment
W₂(20cm) = 20N(35 cm)
W₂ = (20 x 35) / (20)
W₂ = 35 N
Therefore, the weight that will balance the meter stick at 70 cm mark is 35N