Answer:
266.67Watts
Explanation:
Time = 2.5hr to seconds
3600s = 1hr
2.5hrs = 3600×2.5= 9000s
Force = 32N
Distance = 75km to m
1000m = 1km
75km = 1000×75 = 75000m
Power = workdone / time
Work = force × distance
Therefore work = 32N × 75000m
Work = 2400000Nm
Power = work ➗ time
Power = 2400000Nm ➗ 9000s
Power = 266.67Watts
Watts is the S. i unit of power
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Answer:
The focal length of the appropriate corrective lens is 35.71 cm.
The power of the appropriate corrective lens is 0.028 D.
Explanation:
The expression for the lens formula is as follows;
Here, f is the focal length, u is the object distance and v is the image distance.
It is given in the problem that the given lens is corrective lens. Then, it will form an upright and virtual image at the near point of person's eye. The near point of a person's eye is 71.4 cm. To see objects clearly at a distance of 24.0 cm, the corrective lens is used.
Put v= -71.4 cm and u= 24.0 cm in the above expression.
f= 35.71 cm
Therefore, the focal length of the corrective lens is 35.71 cm.
The expression for the power of the lens is as follows;
Here, p is the power of the lens.
Put f= 35.71 cm.
p=0.028 D
Therefore, the power of the corrective lens is 0.028 D.
Answer:
17.64 km/h
Explanation:
mass of car, m = 1000 kg
Kinetic energy of car, K = 1.2 x 10^4 J
Let the speed of car is v.
Use the formula for kinetic energy.
By substituting the values
v = 4.9 m/s
Now convert metre per second into km / h
We know that
1 km = 1000 m
1 h = 3600 second
So, 
v = 17.64 km/h
Thus, the reading of speedometer is 17.64 km/h.
Explanation:
In order to find out if the keys will reach John or not, we can use the formula of projectile motion to find the maximum height reached by the keys:
H = V²Sin²θ/2g
where,
V = Launch Speed = 18 m/s
θ = Launch Angle = 40°
g = 9.8 m/s²
Therefore,
H = (18 m/s)²[Sin 40°]²/(2)(9.8 m/s²)
H = 6.83 m
Hence, the maximum height that can be reached by the projectile or the keys is greater than the height of John's Balcony(5.33 m).
Therefore, the keys will make it back to John.
Answer: work done = 64,000J or 64KJ.
Explanation:
Work is said to be done if a force applied makes the object to move through a distance in the direction of the applied force. Work is the product of force and perpendicular distance in the direction of the applied force. It is represented by W, measured in Joules(J) and a scalar quantity.
Thus, work done(J)= force(N) × distance(m)
From the the question,
applied force= 1600N
distance=40m
Therefore, work= 1600 × 40
W= 64,000J
But, 1 kilojoules = 1000J
Therefore, 64,000J = 64,000 ÷ 1000
= 64KJ
Work done is 64KJ
