Answer:
C) 6 m/s
Explanation:
Given that
m₁=5000 kg
The initial velocity of 5000 kg car =u₁
m₂=10,000 kg
The initial velocity of 10000 kg car =u₂ = 0 m/s
After collision the final speed of the both car,v = 2 m/s
There is no any external force on the system that is why linear momentum will be conserved.
Linear momentum P = m v
m₁u₁ + m₂u₂ = (m₂ + m₁) v
5000 x u₁ + 10000 x 0 = (5000 + 10000) x 2
5000 x u₁ = 15000 x 2
5 x u₁ = 15 x 2
u₁ = 6 m/s
Therefore the answer is C.
C) 6 m/s
The velocity of the submarine immediately after firing the missile is 0.0104 m/s
Explanation:
Mass of the submarine M=50 tonne=
Mass of the missile m=40 kg
velocity of the missile v= 13m/s
we have to calculate the velocity of the submarine after firing
This is the recoil velocity and its expression is derived from the law of conservation of momentum
recoil velocity of the submarine

Answer: 3.5 seconds
EXPLANATION:
Using the formula:
v = u + at
And taking the upwards direction as positive, we have the following information:
u = 35 m/s
a = -10m/s^2 (this is acceleration due to gravity)
At the top of its path, the apple will have a velocity of 0 m/s, therefore:
v = 0m/s
Once you substitute everything into the formula, you get:
0 = 35 + (-10)t
Therefore, t = 35/10 = 3.5 seconds
Answer:
It can be said to be reliable although it is not valid
Explanation:
This is because Reliability means an indicator of consistency, A measure should produce similar or the same results consistently if it measures the same quantity. So does the thermometer measures over 5days but it is not valid because it deviates from the real value