1) 1) While a car travels around a circular track at a constant speed, its A) ve

Question

1) 1) While a car travels around a circular track at a constant speed, its A) velocity is zero. C) inertia is zero. B) acceleration is zero. D) none of the above 2) 2) An 80-km/h airplane flying against a 10 km/h head wind has a ground speed of A) 80 km/h B) 90 km/h _C) 70 km/h D) none of these 3) Galileo's use of inclined planes allowed him to effectively 3) A) increase the acceleration beyond that of free fall B) eliminate friction. C) eliminate the acceleration of free fall. D) slow down the acceleration of free fall 4) If an object falling freely were somehow equipped with an odometer to measure the distance it 4) travels, then the amount of distance it travels each succeeding second would be A) constant. B) doubled. D) less and less each second. greater than the second before. 5) Consider drops of water that leak at a steady rate from a dripping faucet. As the drops fall they5 A) get closer together. -B) remain at a relatively fixed distance from one another C) get farther apart. 6) When a rocket ship accelerating in outer space runs out of fuel, it 6) A) no longer accelerates B) accelerates for a short time, then slows down to a constant velocity C) accelerates for a short time, slows down, and eventually stops 7) A ball is thrown 125 meters upward and then falls the same distance back to Earth. Neglecting air 7 resistance, its total time in the air is B) about 15 seconds. D) about 10 seconds. A) more than 20 seconds. about 5 seconds. C-1

Explanation / Answer

(7)ans

According to the concept of the motion in one dimensional

Given that

Height h=125 m

Now we find the time of flight

Time of the flight T=2*(2gh)^1/2/g

=(8h/g)^1/2

=(8*125/9.8)^1/2

=10.1 sec

The correct option is D

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(8) ans

Given that

acceleration due to gravity g=20 m/s^2

time t=5 sec

now we find the distance at t=5 sec

distance s=1/2at^2

=1/2*20*5^2

=250 m

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(10) ans

Given that

height h=5 m

acceleration due to gravity g=10 m/s^2

now we find the speed to hit the ground

speed v=(2gh)^1/2

=(2*10*5)^1/2

=10 m

the correct option is E

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