Answer:
The time taken by the duck to cross the lake is, t= 4 s
Explanation:
Given data,
The initial speed of the ducks, u = 3 m/s
The final speed of the ducks, v = 7 m/s
The acceleration of the duck, a = 1 m/s²
The formula for the acceleration is,
a = (v - u) / t
∴ t = (v - u) / a
Substituting the given values in the above equation,
t = (7 - 3) / 1
= 4 s
Hence, the time taken by the duck to cross the lake is, t= 4 s
Answer:
230 m/s northeast, 1.8 m/s up
Explanation:
204 kilometres = 204000 metres
15.0 minutes = 900 seconds
Velocity = Distance / Time
= 204000 / 900
= 230 m/s northeast (to 2 sf.)
1.6km = 1600 metres
Velocity = 1600 / 900
= 1.8 m/s up (to 2 sf.)
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Answer:
Car H
Explanation:
Frictional force is a resistant force. It is given as:
F = u*m*g
Where u = coefficient of friction
m = mass
g = acceleration due to gravity
From the formula above, we see that frictional force is dependent on the mass of object and the coefficient of friction.
Since they all have the same tires, the coefficient of friction between the tire and the floor is the same for each car. Acceleration due to gravity, g, is constant.
The only factor that determines the frictional force of each car is the mass. Hence, the more the mass, the more the frictional force.
So, the most massive car will have the most frictional force and hence, will come to a stop quicker than the others. The least massive car will have the least frictional force and so, will take a longer time to stop.
From the calculations, the power expended is 43650 W.
<h3>What is the power expended?</h3>
Now we can find the acceleration from;
v = u + at
u = 0 m/s
v = 95 km/h or 26.4 m/s
t = 6.8 s
a = ?
Now
v = at
a = v/t
a = 26.4 m/s/ 6.8 s
a = 3.88 m/s^2
Force = ma = 850-kg * 3.88 m/s^2 = 3298 N
The distance covered is obtained from;
v^2 = u^2 + 2as
v^2 = 2as
s = v^2/2a
s = (26.4)^2/2 * 3.88
s = 696.96/7.76
s = 90 m
Now;
Work = Fs
Work = 3298 N * 90 m = 296820 J
Power = 296820 J/ 6.8 s
= 43650 W
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Answer:
1) It expresses the rate (top speed) at which it can move with time.
2) P = 20 W
3) h = 18 km
Explanation:
1) Power is the rate of transfer of energy.
⇒ Power = 
i.e P = 
Thus a car's engine power is 44000W implies that the engine of the car can propel the car at this rate. This expresses the rate (top speed) at which it can move with time.
2) m = 400g = 0.4 kg
t = 20 s
h = 100m
g = 10 m/
P = 
= 
= 
P = 20 W
3) u = 600 m/s
g = 10 m/
From the third equation of free fall,
= 
- 2gh
V is the final velocity, U is the initial velocity, h is the height.
0 = 
- 2 x 10 x h
0 = 360000 - 20h
20h = 360000
h = 
= 18000
h = 18 km
The maximum height of the bullet would be 18 km.
