Top Physics 1000 MCQs

Top Physics MCQs

چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔

The kinetic energy of a projectile at the highest point is half of its kinetic energy. The angle of projection is _____?

45°C
60°C
30°C
None of these

(0)

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Explanation

Step 1: Understand the statement
Kinetic energy at the highest point = $\frac{1}{2} \times$ initial kinetic energy.

At the highest point, vertical velocity = 0, only horizontal velocity remains:

$v_{top} = u \cos θ$

Initial KE = $\frac{1}{2} m u^{2}$
KE at top = $\frac{1}{2} m (u \cos θ)^{2}$

Step 2: Set up the equation

$\frac{1}{2} m u^{2} \cos^{2} θ = \frac{1}{2} \times \frac{1}{2} m u^{2}$

Cancel $\frac{1}{2} m u^{2}$ :

$\cos^{2} θ = \frac{1}{2}$ $\cos θ = \frac{1}{\sqrt{2}} ⟹ θ = 45^{\circ}$

A 100 Kg car can accelerate from rest to speed of 25 m/sec in 10s. What average power (in kilo watts) must the engine of the car produce in order to cause this acceleration? Neglect the friction loss.

4125
33.25
3.125
None of these

(0)

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Explanation

Step 1: Find the acceleration
Initial velocity $u = 0$ , final velocity $v = 25 m/s$ , time $t = 10 s$ .

$a = \frac{v - u}{t} = \frac{25}{10} = 2.5 {m/s}^{2}$

Step 2: Find the distance traveled

$s = u t + \frac{1}{2} a t^{2} = 0 + \frac{1}{2} (2.5) (10^{2}) = 0.5 \times 2.5 \times 100 = 125 m$

Step 3: Work done by the engine
Work $W = F \times s = m a \times s$

$W = 100 \times 2.5 \times 125 = 250 \times 125 = 31250 J$

Step 4: Average power

$P = \frac{W}{t} = \frac{31250}{10} = 3125 W$

In kilowatts:

$P = 3.125 kW$

A body rolling freely on the surface of the earth eventually comes to rest because ______?

Its gravitation is less because it is already on the surface
It has mass
It suffers friction
None of these

(0)

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A rock is dropped from a high bridge at the end of 3 seconds of free fall the speed of he rock in cm/s?

2940
30
100
None of these

(0)

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Explanation

Step 1: Use velocity formula for free fall from rest

$v = g t$

where $g = 9.8 {m/s}^{2}$ , $t = 3 s$ .

Step 2: Calculate in m/s

$v = 9.8 \times 3 = 29.4 m/s$

Step 3: Convert to cm/s
$1 m/s = 100 cm/s$

$v = 29.4 \times 100 = 2940 cm/s$

Two tuning forks are sounded, one has a frequency of 250 Hz while the other has a frequency of 245 Hz. What is the frequency of the beats?

235 Hz
250 Hz
5 Hz
None of these

(0)

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Explanation

Step 1: Beat frequency formula
Beat frequency = $∣ f_{1} - f_{2} ∣$ .

Step 2: Given values
$f_{1} = 250 Hz$ , $f_{2} = 245 Hz$ .

Step 3: Calculation

$Beat frequency = ∣ 250 - 245 ∣ = 5 Hz$

If an object is released 19.6 meter above the ground. How long does it take the object to reach the ground? (g = 9.8 m/sec²)

2 seconds
8 seconds
10 seconds
None of these

(0)

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Explanation

Step 1: Use the equation for free fall from rest

$s = \frac{1}{2} g t^{2}$

where $s = 19.6 m$ , $g = 9.8 {m/s}^{2}$ , $t = ?$ .

Step 2: Substitute values

$19.6 = \frac{1}{2} \times 9.8 \times t^{2}$ $19.6 = 4.9 \times t^{2}$

Step 3: Solve for $t^{2}$

$t^{2} = \frac{19.6}{4.9} = 4$ $t = 2 seconds$

A detector with a surface area of 1 square meter is placed in front an operating jackhammer. It measures the power of jackhammer sounds as being 10-³ W. Find the intensity of the jackhammer?

10⁷ w/m²
10-³w/m²
10-¹¹ w/m²
None of these

(0)

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Explanation

Step 1: Intensity formula
Intensity $I = \frac{Power}{Area}$ .

Step 2: Given values
Power $P = 10^{- 3} W$
Area $A = 1 m^{2}$

Step 3: Calculation

$I = \frac{10^{- 3}}{1} = 10^{- 3} {W/m}^{2}$

Which atomic spectroscopy technique is commonly used for the analysis of trace elements in biological samples?

Flame atomic absorption spectroscopy (FAAS)
Inductively coupled plasma optical emission spectroscopy (ICP-OES)
Atomic fluorescence spectroscopy (AFS)
X-ray photoelectron spectroscopy (XPS)

(0)

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In UV-Vis spectroscopy, which law describes the relationship between absorbance, concentration, and path length of a sample?

Lambert-Beer Law
Beer-Lambert Law
Beer’s Law
Lambert’s Law

(0)

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How does a hollow cathode lamp contribute to the performance of atomic absorption spectroscopy (AAS)?

It generates the excitation source for the atoms.
It provides a stable and specific wavelength light source for the measurement.
It serves as the detector for the emitted photons.
It enhances the sensitivity of the analysis.

(0)

PHYSICS

The kinetic energy of a projectile at the highest point is half of its kinetic energy. The angle of projection is _____?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

A 100 Kg car can accelerate from rest to speed of 25 m/sec in 10s. What average power (in kilo watts) must the engine of the car produce in order to cause this acceleration? Neglect the friction loss.

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

A body rolling freely on the surface of the earth eventually comes to rest because ______?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

A rock is dropped from a high bridge at the end of 3 seconds of free fall the speed of he rock in cm/s?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

Two tuning forks are sounded, one has a frequency of 250 Hz while the other has a frequency of 245 Hz. What is the frequency of the beats?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

If an object is released 19.6 meter above the ground. How long does it take the object to reach the ground? (g = 9.8 m/sec²)

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

A detector with a surface area of 1 square meter is placed in front an operating jackhammer. It measures the power of jackhammer sounds as being 10-³ W. Find the intensity of the jackhammer?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

Which atomic spectroscopy technique is commonly used for the analysis of trace elements in biological samples?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

In UV-Vis spectroscopy, which law describes the relationship between absorbance, concentration, and path length of a sample?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

How does a hollow cathode lamp contribute to the performance of atomic absorption spectroscopy (AAS)?

اس سوال کو وضاحت کے ساتھ پڑھیں

Explanation

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