Answer:
(i) 20 m/s
(ii) 0.00625 m/s²
(iii) 25 m/s
Explanation:
(i) The train moves at constant speed when it has no acceleration, meaning when the sum of the forces is zero.
There are two forces acting on the train. The force of the engine pushing the train forward, and the resistance.
∑F = ma
F − R = 0
F = R
The resistance is:
50 N/tonne × (100 tonne + 25 tonne) = 6250 N
Therefore, the force of the engine is 6250 N. The power of the engine is 125 kW. Power is work per time, and work is force times distance, so:
P = W / t
P = Fd / t
P = Fv
125000 Nm/s = (6250 N) v
v = 20 m/s
(ii) The truck becomes uncoupled. The engine is still pushing with 6250 N of force, but the resistance has changed to:
50 N/ton × 100 tonne = 5000 N
∑F = ma
F − R = ma
6250 N − 5000 N = (100 tonne × 2000 kg/tonne) a
a = 0.00625 m/s²
(iii) When the force of the engine matches the new resistance force:
P = Fv
125000 Nm/s = (5000 N) v
v = 25 m/s
The correct answer is
<span>Density
In fact, the density of an object is the ratio between its mass m and its volume V:
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<span>if the size of the object changes, its volume V changes as well, therefore the density d must change.</span>
<span>a cell is almost a little like the medal because they are both have atoms in them</span>
Answer:
Explanation:
Given
Initial Fee for first Plan is
Additional fee
If car drives x miles then total cost
For second Plan
For x miles
If cost of two plans are equal then