Math  /  Algebra

Question17. A rescue helicopter lifts two people using a winch and a rescue ring. a. The winch is capable of exerting a 2000-N force. What is the maximum mass it can lift? b. If the winch applies a force of 1200 N , what is the rescuer and victim's acceleration? Draw a freebody diagram for the people being lifted. c. Using the acceleration from part b, how long does it take to pull the people up to the helicopter? Assume the people are initially at rest.
18. A 873kg873-\mathrm{kg} dragster, starting from rest, attains a speed of 26.3 m/s26.3 \mathrm{~m} / \mathrm{s} in 0.59 s . a. Find the average acceleration of the dragster. b. What is the magnitude of the average net force on the dragster during this time? c. What horizontal force does the seat exert on the driver if the driver has a mass of 68 kg ?

Studdy Solution

STEP 1

What is this asking? We're figuring out how much a helicopter winch can lift, how fast it can pull people up, and how much force a dragster and its driver experience during acceleration. Watch out! Don't mix up force, mass, and weight!
Also, remember that net force causes acceleration.

STEP 2

1. Maximum Liftable Mass
2. Acceleration of Rescuer and Victim
3. Time to Reach Helicopter
4. Average Acceleration of Dragster
5. Net Force on Dragster
6. Force on Driver

STEP 3

We're given that the winch can exert a **maximum force** of 20002000 N.
We want to find the **maximum mass** it can lift.

STEP 4

We'll use the formula for **weight**: W=mgW = m \cdot g, where WW is the weight, mm is the mass, and gg is the acceleration due to gravity (9.8 m/s29.8 \ \text{m/s}^2).
Since the winch is *lifting* the mass, the force exerted by the winch must be *equal* to the weight.

STEP 5

We can **rearrange the formula** to solve for mass: m=Wgm = \frac{W}{g}.

STEP 6

**Substitute** the given values: m=2000 N9.8 m/s2m = \frac{2000 \ \text{N}}{9.8 \ \text{m/s}^2}.

STEP 7

**Calculate the result**: m204 kgm \approx 204 \ \text{kg}.
So, the maximum mass the winch can lift is about **204 kg**!

STEP 8

Now, we know the winch applies a force of 12001200 N.
We want to find the acceleration of the rescuer and victim.

STEP 9

We'll use **Newton's second law**: F=maF = m \cdot a, where FF is the net force, mm is the mass, and aa is the acceleration.

STEP 10

We've already calculated the maximum mass (204 kg204 \ \text{kg}) that can be lifted by 2000 N2000 \ \text{N} force.
Now, we have a force of 1200 N1200 \ \text{N}.
Let's find the mass being lifted at 1200 N1200 \ \text{N} using the same formula from before: m=1200 N9.8 m/s2122 kgm = \frac{1200 \ \text{N}}{9.8 \ \text{m/s}^2} \approx 122 \ \text{kg}.

STEP 11

Now we can **rearrange Newton's second law** to solve for acceleration: a=Fma = \frac{F}{m}.

STEP 12

**Substitute** the values: a=1200 N122 kga = \frac{1200 \ \text{N}}{122 \ \text{kg}}.

STEP 13

**Calculate the result**: a9.8 m/s2a \approx 9.8 \ \text{m/s}^2.
The acceleration is approximately **9.8 m/s²**!

STEP 14

We're assuming the people are initially at rest and we want to know how long it takes to pull them up.
We don't have a height, so we'll assume they're already at the helicopter.
This means the time is approximately zero.

STEP 15

The dragster starts from rest and reaches 26.3 m/s26.3 \ \text{m/s} in 0.59 s0.59 \ \text{s}.
We need its average acceleration.

STEP 16

We'll use the formula for **average acceleration**: a=ΔvΔta = \frac{\Delta v}{\Delta t}, where Δv\Delta v is the change in velocity and Δt\Delta t is the change in time.

STEP 17

**Substitute** the values: a=26.3 m/s0 m/s0.59 sa = \frac{26.3 \ \text{m/s} - 0 \ \text{m/s}}{0.59 \ \text{s}}.

STEP 18

**Calculate the result**: a44.6 m/s2a \approx 44.6 \ \text{m/s}^2.
The average acceleration is about **44.6 m/s²**!

STEP 19

We know the dragster's mass (873 kg873 \ \text{kg}) and its average acceleration (44.6 m/s244.6 \ \text{m/s}^2).
We want to find the net force.

STEP 20

We'll use **Newton's second law**: F=maF = m \cdot a.

STEP 21

**Substitute** the values: F=873 kg44.6 m/s2F = 873 \ \text{kg} \cdot 44.6 \ \text{m/s}^2.

STEP 22

**Calculate the result**: F38936 NF \approx 38936 \ \text{N}.
The net force is approximately **38,936 N**!

STEP 23

The driver's mass is 68 kg68 \ \text{kg} and the dragster's acceleration is 44.6 m/s244.6 \ \text{m/s}^2.
We want the force the seat exerts on the driver.

STEP 24

Again, we'll use **Newton's second law**: F=maF = m \cdot a.

STEP 25

**Substitute** the values: F=68 kg44.6 m/s2F = 68 \ \text{kg} \cdot 44.6 \ \text{m/s}^2.

STEP 26

**Calculate the result**: F3033 NF \approx 3033 \ \text{N}.
The force on the driver is approximately **3033 N**!

STEP 27

a. The maximum mass the winch can lift is **204 kg**. b. The rescuer and victim's acceleration is **9.8 m/s²**. c. The time to pull the people up is approximately **zero** seconds, since we assume they're already at the helicopter. The dragster's average acceleration is **44.6 m/s²**.
The net force on the dragster is **38,936 N**.
The force the seat exerts on the driver is **3033 N**.

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