6. Intro to Forces (Dynamics)

According to Newton's First and Second Laws, why does increasing the stopping distance of a vehicle reduce the severity of a crash?

According to a simplified model of a mammalian heart, at each pulse approximately 20 g of blood is accelerated from 0.25 m/s to 0.35 m/s during a period of 0.10 s. What is the magnitude of the force exerted by the heart muscle?

A man is dragging a trunk up the loading ramp of a mover's truck. The ramp has a slope angle of $20.0$°, and the man pulls upward with a force $\overrightarrow{F}$ whose direction makes an angle of $30.0$° with the ramp (Fig. E$4.4$). How large a force $\overrightarrow{F}$ is necessary for the component $F_x$ parallel to the ramp to be $90.0$ N?

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A man is dragging a trunk up the loading ramp of a mover's truck. The ramp has a slope angle of $20.0$°, and the man pulls upward with a force $\(\overrightarrow{F}\)$ whose direction makes an angle of $30.0$° with the ramp (Fig. E$4.4$). How large will the component $F_y$ perpendicular to the ramp be then?

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Two blocks are attached to opposite ends of a massless rope that goes over a massless, frictionless, stationary pulley. One of the blocks, with a mass of 6.0 kg, accelerates downward at (3/4)g. What is the mass of the other block?

If a car stops suddenly, you feel 'thrown forward.' We'd like to understand what happens to the passengers as a car stops. Imagine yourself sitting on a very slippery bench inside a car. This bench has no friction, no seat back, and there's nothing for you to hold onto. Describe what happens to you as the car slows down.

To extricate an SUV stuck in the mud, workmen use three horizontal ropes, producing the force vectors shown in Fig. E$4.2$. Use the components to find the magnitude and direction of the resultant of the three pulls.

A 27-kg chandelier hangs from a ceiling on a vertical 3.4-m-long wire. What horizontal force would be necessary to displace its position 0.15 m to one side?

An 18-kg child is riding in a child-restraint chair, securely fastened to the seat of a car (Fig. 4–69). Assume the car has speed 45 km/h when it hits a tree and is brought to rest in 0.20 s. Assuming constant deceleration during the collision, estimate the net horizontal force F that the straps of the restraint chair exert on the child to hold her in the chair. <IMAGE>

Two dogs pull horizontally on ropes attached to a post; the angle between the ropes is $60.0$°. If Rover exerts a force of $270$ N and Fido exerts a force of $300$ N, find the magnitude of the resultant force and the angle it makes with Rover's rope.

A constant force is applied to an object, causing the object to accelerate at 10 m/s². What will the acceleration be if the force is halved?

FIGURE EX5.8 shows an acceleration-versus-force graph for three objects pulled by rubber bands. The mass of object B is 0.20 kg. What are the masses of objects A and C? Explain your reasoning.

What is the acceleration, as a multiple of g, if this force is applied to a 110 kg bicyclist? This is the combined mass of the cyclist and the bike.