a) A scientific theory must be able to be proven.
b) A scientific theory has been derived from known facts and always applies.
c) A scientific method should give different results depending on who performs the method.
d) Knowledge of our surroundings usually emerges through an interplay between theory and experiment.
2) The sides of a straight block are measured to 3,202 cm; 0.0012 cm and 11.2 cm, respectively. Calculate the volume of the straightening block and enter it with the correct number of value digits.
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3) A 9.2 dm long and evenly thick rod rests on a support. 0.55 dm from one end, a dynamometer is hung so that the rod will hang horizontally. Then the dynamometer shows 4.4 N. How much does the bar weigh?
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4) A bar AB that is homogeneous and evenly thick has a length of 2.70 m and is rotatable about an axis at A. The bar weighs 25 kg and is kept in equilibrium by a force F which has its point of attack in B. is 45 degrees. How big is the force F?
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Saved!
25 * 9.82 = 245.5 N
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5) A trolley rolls at a constant speed to the right. On the cart is an upward cannon that suddenly shoots a bullet. The carriage continues to the right with the same speed as before. Where does the bullet end up when it falls? For a detailed reasoning.
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6) A river is 200 m wide. The water in the river flows at a speed of 2.5 m / s. A motorboat steers across the river at its maximum speed, which in stagnant water is 5.0 m / s. The boat is constantly heading perpendicular to the banks of the river. Where does the motorboat land on the other shore?
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7) A ball with a mass of 2.0 hg moves at a constant speed in a circular path. The radius of the track is 1.5 m and it takes the ball 3.0 seconds to move one turn. How big is the centripetal force?
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8) A bullet moves at a constant speed. Can we then safely say that the resultant of the forces acting on the bullet is zero? Motivate and discuss your answer.
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9) A conductor is located between the poles of a permanent magnet. The current in the conductor goes in the direction of the plane of the paper (away from the reader). How is the force acting on the leader directed?
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a) To the right of the figure
b) To the left in the figure
c) Downwards in the figure
d) Upwards in the figure
10) Protons enter horizontally from the left between two large metal plates at a speed v = 0.80 Mm / s. The plates are connected to a voltage source with the pole voltage U. Between the plates there is a homogeneous magnetic field with a flux density of 38 mT directed perpendicular to the plane of the paper. The distance between the plates is 1.5 cm. They want the protons to continue with unchanged direction and speed between the plates. Which of the plates should be connected to the positive pole of the voltage source and how large should the voltage U be?
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11) The magnetic flux Φ through a 700-speed coil decreases linearly with time according to the diagram below. Calculate the voltage across the coil at time t = 1.0 ms.
12) The current in a coil with an inductance of 35 mH has a growth rate of 6.2 A / s at a given moment. What is the instantaneous value of the ems induced in the coil?
motionless puck as shown on the picture above. The net force that the stick applies on the puck is 150N and the contact lasts for 7.5 ms. The mass of the puck is 166 g.
A) (1 point) Calculate the acceleration of the puck under the influence of the net force.
B) (2 points) Calculate the puck's change in momentum due to the impulse applied by the hockey stick.
C) (1 point) What is the velocity of the puck once it leaves the stick?
Puck travels over rough ice and comes to a stop after 25 m. The force diagram below shows all forces acting on the puck during that travel.
Screen Shot 2020-11-02 at 2.04.05 PM.png
D) (1 point) Calculate the work done on the puck by gravitational force.
E) (1 point) Calculate the work done on the puck by normal force.
F) (2 points) Calculate work done by friction force on the puck.
CNX_UPhysics_09_03_HockeyPuck.jpg
Now stationary, the puck (red) collides with a blue puck of the mass .332 kg moving to the left with velocity of 2.5 m/s. If collision is perfectly elastic calculate:
H) (2 points) Total momentum of blue+red puck system before collision?
I) (1 point) What is the total momentum of blue+red puck system after collision? How do you know?
J) (2 points) What is the velocity of the blue puck after collision?
at her at speed of 40m/s. She shouts, “Youch!’ because the fast-moving ball hurts her hands. She quickly learns how to move her arms and hands along with the ball as she catches it to reduce the magnitude of the impulse force. If the contact time of the collision is increased from the original value of 3.5ms with no arm or hand movement, to 8.5ms in the manner described, how do the magnitudes of the average impulse forces compare? Calculate both of these average forces.