Problem 4.15 A compact car has a maximum acceleration of5.0m/s2 when it carries

Question

Problem 4.15

A compact car has a maximum acceleration of5.0m/s2 when it carries only the driver and has a total mass of 1300kg.

What is its maximum acceleration after picking up four passengers and their luggage, adding an additional 400 kg of mass? Express your answer to two significant figures and include the appropriate units.

Problem 4.20

Scallops eject water from their shells to provide a thrust force. (Figure 1) shows a smoothed graph of actual data for the initial motion of a 25g scallop speeding up to escape a predator.

Part A: What is the magnitude of the net force needed to achieve this motion? Express your answer to two significant figures and include the appropriate units.

Part B How does this force compare to the 0.25N weight of the scallop? a.This force is 1/25 of the weight of the scallop b.This force is 1/5 of the weight of the scallop. c.This force is 1/15 of the weight of the scallop d.This force is 1/10 of the weight of the scallop.

Problem 4.22

In t-ball, young players use a bat to hit a stationary ball off a stand. The 140 g ball has about the same mass as a baseball, but it is larger and softer. In one hit, the ball leaves the bat at 12m/s after being in contact with the bat for 2.0ms . Assume constant acceleration during the hit.

Part A: What is the acceleration of the ball? Express your answer to two significant figures and include the appropriate units.

Part B: What is the net force on the ball during the hit? Express your answer to two significant figures and include the appropriate units.

Problem 4.31

Your car is accelerating to the right from a stop. Identify all forces acting on the object and draw the free-body diagram. Draw the vectors starting at the black dot. The location and orientation of the vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded.

Explanation / Answer

1)

apply F = ma

m1a1 = m2a2

a2 =1300*3/ (1400+300)

a2 = 2.294 m/s^2

2) mass , m = 0.025 kg

slope of the graph is accelerartion

so from graph slope = (0.2-0)/(0.2-0) = 1

so acceleartion is 1 m/s2

force needed for this acceleartion , F = mass*aceleration = 0.025*1 = 0.025 N

so force compare to the 0.25N weight of the scallop is 0.025/0.25 = 1/10

so option (c) is correct

3) acceleration is rate of change of velocity

so acceleartion, a = (12-0)/ (2*10-3) = 6000 m/s2

net froce is mass*acceleration = 0.14*6000 = 840N

4)the forces which will be applicable on the car are

air resistance

Normal force

kinetic friction force

weight

5)the forces acting on the system skydiver-parachute are

Tension, T

Thrust F

Weight, w

Air resistance, D

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.