1) Newton’s first law states that an object at rest will remain at rest and an o

Question

1) Newton’s first law states that an object at rest will remain at rest and an object in motion will continue moving at the same speed and in the same direction unless acted upon by an external force. Are there forces acting on the marble as it rolls down the incline? If so, which one(s)?

2)   Does the marble’s velocity increase, decrease, or remain constant as it rolls down the ramp? Explain with reference to your data.

3)   Does the marble’s acceleration increase, decrease, or remain the same as it rolls down the ramp? Why is this the case?

4)   What would you expect to happen to the value of the marble’s acceleration if the ramp was steeper? [If you have trouble answering this, repeat the experiment with a steeper ramp.]

5)   When driving with a friend you set your sunglasses on the dashboard of his car right by the windshield in front of you. He says you shouldn’t do that because if he suddenly slams on his brakes it will fly back and hit you in the face. Does this make sense? Why or why not?

6)   A fragment of rock breaks off from a cliff and falls. Ignoring air resistance, what would you expect its speed be after one second of falling? After two seconds? Why?

7)    Suppose you join a mission to Mars, where the acceleration of gravity is gM = 3.71 2. How would you expect the results of your experiment to differ?

Height of Ramp 0.048 m Angle of Incline 20 TRIAL Distance (x) m Time (t) s Velocity (v) m/s Acceleration (a) m/s2 o. 0.428 0.507 21 03 1.339 0.448 0.335 3 0.3 1.19 11 0.504 0.423 0.3 1.22 0.403 0.492 51 0.3 1.328 0.452 0340 Average 1.2524 Average 0.480 Average 0.386 61 0.61 1.879 0.639 0.340 7 0.6 1.86 0.645 0.347 8 0.6 1.983 0.305 0.605 91 0.6 .721 0.697 0.405 101 0.6 1.921 0.325 0.625 Average 0.344 Average 1.8728 Average 0.642 1 0.9 2.342 0.769 0.328 12 0.9 2.454 0.733 0.299 131 0.9 2.353 0.765 0.325 0.299 2.452 15 0.91 2.314 0.778 0.336 Average 2.383 Average 0.756 Average 0.318

Explanation / Answer

Q1. forces acting on the marble are:

a) weight of the marble, in vertically downward direction

b) normal force from the inclince along 90 degrees on the inclince

c) friction force on the marble, in opposite direction to the motion of the marble

Q2. marble's velocity increases as it rolls down the ramp

as can be seen from the data , as distance increases the speed increases

Q3. marble's acceleration remains constant

as forces acting on the marble are constant.

Q4. if ramp is steeper, the normal force will decreases

and friction force will decreases

so net force on the marble will increase

and hence the acceleration of the marble will increase.

Q5. it wont hit you in the face but your face will hit the widnshield

reason:
when you are in motion, due to inertia of motion, you wont suddenly stop and you will hit the windshield.

same will happen with the sunglasses and it will hit the front of the car.

Q6. speed after one second=acceleration due to gravity*time

=9.8*1=9.8 m/s

speed after 2 seconds=9.8*2=19.6 m/s

Q7. as acceleration of gravity is lesser, net force on the object will be lesser

and hence acceleration will be lesser.

so for a given distance, velocity at the end of reaching that distance will be lesser.

note:

equations of importance:

final velocity=initial velocity+acceleration*time

displacement=initial velocity*time+0.5*acceleration*time^2

final velocity^2-initial velocity^2=2*acceleration*displacement

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