Author: admin
-
Practice Problems
1 . A 5 kg bowling ball is rolled with a velocity of 10 m/s. What is its momentum? 2 . (credit: modification of work from Pinterest) A 155-g baseball is incoming at a velocity of 25 m/s. The batter hits the ball as shown in the image. The outgoing baseball has a velocity of 20 m/s…
-
Venus Williams’ Racquet
During the 2007 French Open, Venus Williams (Figure 8.3) hit the fastest recorded serve in a premier women’s match, reaching a speed of 58 m/s (209 km/h). What was the average force exerted on the 0.057 kg tennis ball by Williams’ racquet? Assume that the ball’s speed just after impact was 58 m/s, the horizontal…
-
A Football Player and a Football
(a) Calculate the momentum of a 110 kg football player running at 8 m/s. (b) Compare the player’s momentum with the momentum of a 0.410 kg football thrown hard at a speed of 25 m/s. STRATEGY No information is given about the direction of the football player or the football, so we can calculate only…
-
Saving Lives Using the Concept of Impulse
Cars during the past several decades have gotten much safer. Seat belts play a major role in automobile safety by preventing people from flying into the windshield in the event of a crash. Other safety features, such as airbags, are less visible or obvious, but are also effective at making auto crashes less deadly (see Figure…
-
Hand Movement and Impulse
In this activity you will experiment with different types of hand motions to gain an intuitive understanding of the relationship between force, time, and impulse. Procedure: What are some other examples of motions that impulse affects?
-
Newton’s Second Law in Terms of Momentum
When Newton’s second law is expressed in terms of momentum, it can be used for solving problems where mass varies, since Δ𝐩=Δ(𝑚𝐯)Δp=Δ(�v) . In the more traditional form of the law that you are used to working with, mass is assumed to be constant. In fact, this traditional form is a special case of the law, where…
-
Momentum, Impulse, and the Impulse-Momentum Theorem
Linear momentum is the product of a system’s mass and its velocity. In equation form, linear momentum p is 𝐩=𝑚𝐯.�=��. You can see from the equation that momentum is directly proportional to the object’s mass (m) and velocity (v). Therefore, the greater an object’s mass or the greater its velocity, the greater its momentum. A large, fast-moving object has greater momentum…
-
Nuclear Power
Technically, there are two kinds of nuclear power—fusion and fission. Humans have not quite figured out how to make an efficient fusion reactor, so let me focus on a fission reaction. The fission reactor starts with a heavy atom like uranium-235 and hits it with a neutron. The atom absorbs this neutron to become uranium-236.…
-
Wind Power
I wonder what else we could get to turn one of those electric turbines. What if we put a large blade on the front of the turbine so that wind could turn it. Yup. That’s wind power. Since energy is conserved, that must mean that when you get electrical energy from the wind turbine then…
-
Hydroelectric Power
I would like to call this “hydropower” instead of hydroelectric, but that’s the common name that everyone uses. The thing is that we have been using some form of hydropower for a long time—the water wheel is much older than the invention of electricity. In terms of electrical energy, it’s not too complicated. In fact…