Question

Q1 A car moves twice as fast as another similar car (same mass). The faster car has

four times the kinetic energy of the slower car

half the kinetic energy of the slower car

same kinetic energy as the slower car

twice the kinetic energy of the slower car

Q2:A wave that completes 200 vibrations in 10 seconds has a frequency of

2000 Hz

20 Hz

0.5 Hz

10 Hz

Answer 1

1.

Kinetic energy is given by,

K = 0.5*m*v^2

given, both cars have same mass.

then, K1/K2 = (v1/v2)^2

Let, v1 = speed of faster car = v

then, v2 = speed of slower car = v/2

So,

K1/K2 = (v/v/2)^2 = 4

K1 = 4*K2

therefore, The faster car has four times the kinetic energy of the slower car.

Correct option is A.

2.

Given, total cycles = 200

total time required = 10 sec.

then, frequency(f) = (Total cycles)/(Total time required) = 200/10 s^-1

f = 20 Hz

So, correct option is B.

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