Answer:

Explanation:
Let's use the decay equation.

Where:
- A is the activity at t time
- A₀ is the initial activity
- λ is the decay constant
We know that 
So we have:




Therefore, the half-life of the source is 6 hours.
I hope it helps you!
Answer:
1. 
2.
3. 
4. 
Explanation:
1. The frequency of rotation is given by:

Where:
ω: is the angular speed = 50 rotations (revolutions) in 25 s.
We need to convert the units of ω.

Now, the frequency is:

2. The frequency is:
We know:
5 laps = 5 revolutions
t: time = 450 s
3. The frequency of the pendulum is:

4. We have:
θ: number of revolutions = 48 rev
f = 12 Hz
t =?
The time can be calculated as follows:


I hope it helps you!
Answer:
a = -8.912 m/s²
Explanation:
Given,
The initial velocity of the car, u = 28 m/s
The final velocity of the car, v = 0
The distance traveled by car, d = 88 m
The velocity displacement relation is given by the formula
v = d/t
∴ t = d/v
Substituting in the above values in the given equation
t = 88/28
= 3.142 s
The acceleration is given by the formula
a = (v-u)/t
= (0 - 28)/3.142
= -8.912 m/s²
The negative sign is that the car is decelerating.
Hence, acceleration a = -8.912 m/s²
The work of Brian mind interface is to learn that’s my guess lol
Answer:
light travels faster than sound