Force and Motion Practice Test 5
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When a body is dropped from a tower, then there is an increase in its -
When a body is dropped from a tower, its velocity increases continuously due to the gravitational force pulling it downward.
This acceleration causes the body to gain speed as it falls. At the same time, the body's potential energy decreases because it is converting into kinetic energy—the energy of motion—as the body descends.
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The velocity of a train increases uniformly from 20 km/h to 60 km/h in 4 hour. The distance travelled by the train during this time is -
Explanation:
3 / 15
Which of the following changes when a particle is moving with uniform velocity?
When a particle is moving with uniform velocity then its speed also zero and acceleration become zero.
The position vector of the particle changes as time progresses, even if the particle is moving with uniform velocity, because its location in space is continuously changing.
4 / 15
Velocity of an oblique projectile in its flight –
During the flight of an oblique projectile:
5 / 15
A ball is thrown at an angle θ with the horizontal. Its horizontal range is equal to its maximum height. This is possible only when the value of tan θ is:
6 / 15
In the motion of a projectile freely under gravity, its:
Hint: An External Force by gravity is Present Throughout the Motion so Momentum cannot Be Conserved
7 / 15
For a projectile, the physical quantity that remains constant is –
Only the horizontal component of velocity and acceleration remain constant for a projectile, as they are not affected by the vertical forces of gravity.
Explanation of Incorrect Options:
Vertical component of velocity and kinetic energy: Both change continuously due to gravity.
Potential energy and kinetic energy: They constantly convert from one form to another throughout the projectile's motion.
Potential energy and acceleration: Acceleration is always due to gravity, which affects both potential and kinetic energy, making them change.
8 / 15
A force can cause
A force can cause a stationary object to start moving, a moving object to decrease speed, and a moving object to change its direction of motion.
9 / 15
Fahad Safi daily walk 7m east, 8m south, then 4m west. What is the magnitude of the displacement he cover?
To find the magnitude of the displacement of the car, we must represent each velocity of the car as a vector. We will then add the vectors. Finally, we will find the magnitude of the resulting velocity vector, which will give us speed.
10 / 15
A cannon ball is fired at an angle of 45 degrees from the horizontal. Which of the following describes the kind of motion experienced by the cannon ball in the y-axis and the x-axis respectively?
The cannon ball has a two-dimensional motion, specifically projectile motion. Any two-dimensional motion consists of two one-dimensional motions happening at the same time. This is why we break vectors into components, so we can analyze each one-dimensional motion separately. The motion in the y-axis and the x-axis are connected by the time variable, since they happen at the same time. For projectile motion, we have that on the y-axis (the vertical axis) a constant acceleration (gravity) is acting on the cannon ball. For the y-axis motion with constant acceleration or free fall (which is motion with constant acceleration where the acceleration is gravity) are correct choices. On the x-axis (the horizontal axis), there is no acceleration acting on the cannon ball horizontally. Therefore, on the x-axis the cannon ball experiences motion with constant velocity. Then the only answer choice that describes the motion of the cannon ball in each axis correctly is: y-axis: motion with constant acceleration and x-axis: motion with constant velocity.
11 / 15
In five seconds a runner moves from the 50m mark to the 75m mark along a straight path. What is the runner's average velocity in m/sec ?
To find the average velocity, the displacement needs to be measured. The displacement the difference between The final position and the initial position.
75m−50m=25m
Using the equation for velocity, velocity=displacement/time, we can find the average velocity.
v=25/5=5ms
12 / 15
Fahad Safi dropped a 2kg ball from Minare-Pakinstan. If the ball takes four seconds to hit the ground, what is the ball's speed in m/s right before it hits the ground?
We are given the time that the ball is in the air and the acceleration. Since the ball is dropped, we can also tell that the initial velocity is zero (starts from rest). Using these given values, we can calculate the final velocity using the appropriate motion equation.
The final velocity is negative because the ball is traveling downward; however, the question asks for speed, allowing us to disregard the vector indicator. Speed cannot be negative.
13 / 15
Fahad Safi dropped a 2kg ball from Minare-Pakinstan. If the ball takes four seconds to hit the ground, what is the height from which the ball was dropped?
The resulting displacement is negative because the ball is traveling downward; however, the height will be the absolute value of the displacement, giving out final answer.
14 / 15
A 3.0 kg mass undergoes an acceleration given by a = (2.0i + 5.0j)m/s2. Find the resultant force F and its magnitude respectively.
15 / 15
A displacement–time graph is a straight line making 45° with the time axis. This shows:
Straight line with constant slope on s–t graph means constant speed.
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