Q. A train leaves a station and travels at 90 km/h. Another train leaves the same station 30 minutes later and travels at 120 km/h. How far from the station will they meet?
A.90 km
B.120 km
C.150 km
D.180 km
Solution
Let the distance be d. Time taken by first train = d/90. Time taken by second train = d/120. Setting up the equation gives d = 150 km.
Q. A train leaves a station at 80 km/h and another train leaves the same station 30 minutes later at 100 km/h. How far from the station will they meet?
A.100 km
B.120 km
C.150 km
D.180 km
Solution
Let the time taken by the first train be t hours. Distance = speed * time. 80t = 100(t - 0.5). Solving gives t = 2 hours, so distance = 80 * 2 = 160 km.
Q. A train moving at 72 km/h passes a platform 300 m long. How long does it take to cross the platform completely?
A.10 seconds
B.15 seconds
C.20 seconds
D.25 seconds
Solution
Total distance = Length of train + Length of platform. If length of train is L, time = (L + 300)/20 m/s. Assuming L = 300 m, time = (300 + 300)/20 = 30 seconds.
Q. A train travels at a speed of 90 km/h and a car at 60 km/h. If they start from the same point and travel in the same direction, how far apart will they be after 1 hour?
A.30 km
B.20 km
C.10 km
D.40 km
Solution
Relative speed = 90 - 60 = 30 km/h. Distance apart after 1 hour = 30 km.
Q. A transformer operates on the principle of electromagnetic induction. If the primary coil has 100 turns and the secondary coil has 50 turns, what is the relationship between the primary and secondary voltages?
A.V_primary = 2 * V_secondary
B.V_primary = 0.5 * V_secondary
C.V_primary = V_secondary
D.V_primary = 4 * V_secondary
Solution
The voltage ratio in a transformer is given by the turns ratio. Therefore, V_primary/V_secondary = N_primary/N_secondary = 100/50 = 2, which means V_primary = 2 * V_secondary.
Q. A transformer operates on the principle of electromagnetic induction. What is the primary function of a transformer?
A.To increase voltage
B.To decrease voltage
C.To convert AC to DC
D.To store energy
Solution
A transformer is designed to increase or decrease the voltage in an AC circuit through electromagnetic induction, depending on the turns ratio of the primary and secondary coils.
Q. A tree is 15 meters tall. From a point on the ground, the angle of elevation to the top of the tree is 30 degrees. How far is the point from the base of the tree?
Q. A tuning fork produces a sound wave of frequency 440 Hz. What is the wavelength of the sound wave in air (speed of sound = 340 m/s)?
A.0.77 m
B.0.85 m
C.0.90 m
D.1.00 m
Solution
The wavelength λ can be calculated using the formula λ = v/f, where v is the speed of sound and f is the frequency. Thus, λ = 340 m/s / 440 Hz = 0.77 m.
