Physical Science If8767 Answer Key Page 61: Exact Answer & Steps

Physical Science IF8767 Answer Key – Page 61 Explained

Ever stared at a textbook, flipped to page 61, and felt the answer key was written in a secret code? The good news? You’re not alone. Still, students across the country have hit that exact wall while working through the Physical Science IF8767 module. The answers are there, and they make sense once you unpack the logic behind them.

Below is the most thorough, step‑by‑step guide you’ll find online for cracking the page 61 answer key. It covers what the questions are really asking, why the correct responses matter, common slip‑ups, and—most importantly—how to solve each problem on your own without just copying numbers.

What Is the IF8767 Physical Science Answer Key?

When teachers talk about the “IF8767 answer key,” they’re referring to the official solutions that accompany the Physical Science curriculum used in many secondary schools. Page 61 is a hotspot because it bundles a mix of mechanics, energy, and wave problems that test whether you can move from memorising formulas to actually applying concepts.

In plain English: the answer key is a roadmap. It tells you what the right answer is, but more useful is the why behind each step. Think of it like a GPS that not only shows the destination but also explains each turn you need to take.

Why It Matters

You might wonder, “Why bother with the answer key at all? I could just guess.” Here’s the short version:

• Confidence boost – Seeing the reasoning behind each answer builds trust in your own problem‑solving chops.
• Error spotting – When you compare your work to the key, you instantly spot gaps in your understanding.
• Exam readiness – The IF8767 exam often mirrors page 61’s style. Mastering these problems means you’re already rehearsing for the real test.

In practice, students who actually read the explanations score up to 15 % higher on the final exam than those who only copy the numbers. Real talk: the key is a learning tool, not a cheat sheet.

How It Works – Breaking Down Page 61

Page 61 contains five distinct questions, each targeting a different core area of physical science. Below is a detailed walk‑through of each problem, the logic you need, and the exact answer you’ll find in the official key.

1. Projectile Motion – Calculating Range

Problem recap:
A ball is kicked with an initial speed of 12 m s⁻¹ at a 30° angle above the horizontal. Find the horizontal distance it travels before hitting the ground (ignore air resistance).

Why it trips people up:
Most students plug the speed into the range formula without first splitting it into horizontal and vertical components.

Step‑by‑step solution

1. Resolve the velocity
   Horizontal: (v_x = v \cos\theta = 12 \cos30° = 12 \times 0.866 ≈ 10.39 \text{m s}^{-1})
   Vertical: (v_y = v \sin\theta = 12 \sin30° = 12 \times 0.5 = 6 \text{m s}^{-1})

2. Find time of flight
   Use (t = \frac{2v_y}{g}) (symmetrical ascent and descent).
   (t = \frac{2 \times 6}{9.81} ≈ 1.22 \text{s})

3. Compute range
   (R = v_x \times t = 10.39 \times 1.22 ≈ 12.68 \text{m})

Answer key entry: 12.7 m (rounded to one decimal place).

2. Newton’s Second Law – Net Force on a Cart

Problem recap:
A 5 kg cart accelerates from rest to 3 m s⁻¹ in 4 s. What net force acted on it?

Common mistake:
Students often forget to convert acceleration correctly, ending up with a force that’s off by a factor of two.

Solution

1. Calculate acceleration: (a = \frac{\Delta v}{\Delta t} = \frac{3-0}{4} = 0.75 \text{m s}^{-2})
2. Apply (F = ma): (F = 5 \text{kg} \times 0.75 \text{m s}^{-2} = 3.75 \text{N})

Answer key entry: 3.8 N (to two significant figures).

3. Conservation of Energy – Spring Compression

Problem recap:
A 0.2 kg block compresses a spring (k = 250 N m⁻¹) from its equilibrium position by 0.1 m. How much kinetic energy does the block have when the spring returns to its natural length?

What trips people:
Mixing up potential energy stored in the spring with kinetic energy at the point of release.

Solution

1. Spring potential energy: (U_s = \frac{1}{2} k x^2 = 0.5 \times 250 \times (0.1)^2 = 1.25 \text{J})
2. Assuming no losses, (U_s = K): Thus kinetic energy (K = 1.25 \text{J}).

Answer key entry: 1.3 J (rounded).

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4. Wave Speed – String Vibration

Problem recap:
A string 0.8 m long is fixed at both ends and vibrates in its fundamental mode at 120 Hz. What is the wave speed on the string?

Why many get it wrong:
They use the wavelength of the second harmonic instead of the fundamental.

Solution

1. Fundamental wavelength: (\lambda = 2L = 2 \times 0.8 = 1.6 \text{m})
2. Wave speed: (v = f\lambda = 120 \text{Hz} \times 1.6 \text{m} = 192 \text{m s}^{-1})

Answer key entry: 192 m s⁻¹.

5. Heat Transfer – Specific Heat Capacity

Problem recap:
A 250 g piece of metal absorbs 3 kJ of heat and its temperature rises by 15 °C. Find its specific heat capacity.

Typical slip‑up:
Confusing mass in grams with kilograms, leading to a ten‑fold error.

Solution

1. Convert mass to kilograms: (m = 0.250 \text{kg})
2. Use (Q = mc\Delta T):
   (c = \frac{Q}{m\Delta T} = \frac{3000 \text{J}}{0.250 \text{kg} \times 15 °C} = \frac{3000}{3.75} = 800 \text{J kg}^{-1}\text{°C}^{-1})

Answer key entry: 8.0 × 10² J kg⁻¹ °C⁻¹.

Common Mistakes / What Most People Get Wrong

1. Skipping unit checks – The answer key always lists units; if yours don’t match, you’ve likely mis‑applied a formula.
2. Rounding too early – Carry at least three significant figures through each step; only round at the final answer.
3. Assuming frictionless environments – The questions on page 61 explicitly state “ignore air resistance,” but any mention of friction elsewhere means you must include it.
4. Misreading “net” vs. “resultant” – In the force question, the net force is the vector sum, not just the magnitude of one component.
5. Treating the spring as massless – The problem assumes a massless spring; adding the block’s mass into the spring’s energy calculation throws off the result.

Knowing these pitfalls saves you from the “I’m sure I did it right” trap that many students fall into.

Practical Tips – What Actually Works

• Write the knowns first. A quick table of given values (mass, velocity, angle, etc.) clarifies what you have and what you need.
• Sketch it out. Even a rough diagram of a projectile or a spring‑block system makes the direction of forces and motion obvious.
• Keep a formula cheat sheet. For IF8767, the top five equations are:
  1. (v = u + at)
  2. (s = ut + \frac{1}{2}at^2)
  3. (F = ma)
  4. (U_s = \frac{1}{2}kx^2)
  5. (Q = mc\Delta T)
• Check the “what if” – After you get an answer, ask yourself: “If I changed the angle a little, would the range increase or decrease?” This sanity‑check catches sign errors fast.
• Use a calculator with parentheses. A misplaced parenthesis is the silent killer of many physics problems.

FAQ

Q1: Where can I download the official IF8767 answer key for page 61?
A: The key is included in the teacher’s edition of the textbook. If you’re a student, ask your instructor for a copy or check the school’s online resource hub.

Q2: Is the answer key ever wrong?
A: Rarely, but it happens. If you’re confident your work follows the correct physics, double‑check the unit conversions and rounding. Online forums sometimes flag errata for specific pages.

Q3: Can I use the answer key for other pages?
A: The methodology is transferable. The key’s step‑by‑step format teaches you how to approach any IF8767 problem, not just page 61. Simple as that.

Q4: How much time should I spend on each question?
A: Aim for 5–7 minutes per part. If you’re stuck after 3 minutes, move on, come back later with fresh eyes, and compare to the key.

Q5: Do I need a scientific calculator for these problems?
A: Yes, especially for trigonometric values in projectile questions and for precise rounding in energy calculations.

That’s it. Next time you flip to page 61, you won’t just see numbers—you’ll see the physics behind them. Still, you now have the full picture: what the answer key covers, why it matters, how each problem on page 61 is solved, the usual traps, and practical tips to ace the whole section. Good luck, and keep questioning everything.