Question

In: Physics

1.D Which of the following statements is true and why? A. speed can be negative. B....

1.D Which of the following statements is true and why?

A. speed can be negative.

B. acceleration is always positive.

C. constant speed implies constant velocity.

D. acceleration and velocity always have the same direction.

E. constant velocity implies constant speed.

2.A If a net non-zero force is acting on an object, which of the following must be true?

A. The object is moving with constant velocity.

B. The speed is increasing.

C. The speed is changing.

D. The object has a non-zero acceleration.

E. The acceleration is changing

5.A What is impulse and what is momentum? How can the second Newton’s law be formulated these concepts?

7.A A spring-loaded toy gun is used to launch a 5-gram plastic ball. The compressed spring in the gun stores 0.025 J of energy. When the trigger is pulled the spring is released and shoots the ball back out. If all the spring energy is transferred to the ball, what is the ball's speed as it leaves the barrel?

7.B A 1.5-kg cart starts at rest at the top of the frictionless hill shown below. When it reaches the bottom it is traveling at 30 m/sec. What is the height of the hill?

7.C A 400-gram ball is released from a 180 cm height above the floor (with zero initial velocity). At the moment just before it reaches the floor its speed is measured to be 5.92 m/s. How much energy was lost into heat?

8.A A 500-kg sports car accelerates from rest to 30 m/s in 10 seconds. What is the power of the car’s engine?

8.B The brain consumes energy at 10 times the rate of the rest of the body per gram of tissue. The average power consumption of a typical adult’s brain about 20 W. How much energy on average is consumed by brain during a 2-hr exams?

8.C An elevator motor lifts a 1000-kg elevator a height of 60 meters. How much power must the motor supply to do this in 40 sec at a constant speed?

Expert Solution

genius_generous answered 2 years ago

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