Answer:
a. Acceleration, a = 1.88 m/s²
b. Time, t = 7.87 seconds.
Explanation:
Given the following data;
Initial velocity, U = 14.5m/s
Final velocity, V = 29.3m/s
Distance, S = 172m
a. To find the acceleration of the speedboat;
We would use the third equation of motion;
V² = U² + 2aS
Substituting into the formula
29.3² = 14.5² + 2a*172
858.49 = 210.25 + 344a
344a = 858.49 - 210.25
344a = 648.24
a = 648.24/344
Acceleration, a = 1.88 m/s²
b. To find the time;
We would use the first equation of motion;
V = U + at
29.3 = 14.5 + 1.88t
1.88t = 29.3 - 14.5
1.88t = 14.8
Time, t = 14.8/1.88
Time, t = 7.87 seconds.
Answer:
The volume of water is 139 mL.
Explanation:
Due to the Law of conservation of energy, the heat lost by coffee is equal to the heat gained by the water, that is, the sum of heats is equal to zero.

The heat (Q) can be calculated using the following expression:

where,
c is the specific heat of each substance
m is the mass of each substance
ΔT is the difference in temperature for each substance
The mass of coffee is:

Then,

The volume of water is:

An LED is useful because when a current passes through it, it gives out light.
The new gravitation force at the new location is 40 N
Explanation:
The weight of the astronaut is given by the equation
(1)
where
m is the mass of the astronaut
g is the acceleration of gravity
The acceleration of gravity at a certain distance
from the centre of the Earth is given by

where G is the gravitational constant and M is the Earth's mass. So we can rewrite eq.(1) as

When the astronaut is on the Earth's surface,
(where R is the Earth's radius), so his weight is

Later, he moves to another location where his distance from the Earth's surface is 3 times the previous distance, so the new distance from the Earth's centre is

Therefore, the new weight is

Which means that his weight has decreased by a factor 16: therefore, the new weight is

Learn more about gravitational force:
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