The magnitude of the horizontal acceleration of sphere a is

Asked by admin @ 28/10/2021 in Physics viewed by 226 People

PHYSICS PLEASE HELP

1.) When an object is dropped from the top of a tall cliff, your teacher tells you to use -10 m/s2 for the approximate acceleration due to gravity. What sign should the displacement of the object have and why?
A) The displacement should be positive, because it only moves in one direction.
B) The displacement should be positive, because this choice would make calculations easier
C) The displacement should be negative, because the negative represent a downward direction.
D) The displacement should be positive, because you can never have less than zero displacement.
2) A cannonball is fired horizontally with an initial velocity of 20 m/s off a cliff that is 10 m from the ground. if the initial velocity is doubled what will be the affect on the time and horizontal distance?
A) Both the time and horizontal distance will double.
B) Neither the time or horizontal distance will change.
C) The time won't change, but horizontal distance will double.
D) The time will double, but the horizontal distance won't change.
3) Ben and Jerry took a four day mountain hike during summer vacation. The distance traveled each day is seen in the illustration. They traveled to point A on day one; point B on day two. They turned around and went back home on day three because Jerry forgot his allergy medicine. Their hike ended at point D. How does Ben and Jerry's total displacement compare to their distance traveled?
A) Displacement is 0 km and distance travled is 30 km.
B) Dispalcement is 30 km and distance traveled is 30 km.
C) Displacement is 30 km but distance traveled is 110 km.
D) Displacement is 110 km and distance traveled is 110 km.
4) A stone is launched from the ground, at a 70° angle, with an initial velocity of 120 m/s. Once you determine when the stone hits the ground, which equation would you use to find its final horizontal distance?
A) x = 41t
B) x = 60t
C) x = 84.7t
D) x = 120t
5) Sally walks 10 meters forward and then 5 meters backwards. Which statement most accurate describes the magnitude of her displacement and distance travelled?
A) Sally's displacement is 5m less than her distance travelled.
B) Sally's displacement is 10m less than her distance travelled.
C) Sally's displacement is 5m greater than her distance travelled.
D) Sally's displacement is 10m greater than her distance travelled.
6) Eric decided to go for a walk from his home. He headed 6 meters east and x meters north. The angle formed by the displacement vector and the horizontal vector is 37°. What is the length of the displacement vector?
A) 7.5 m
B) 9 m
C) 10 m
D) 12 m
7) If a soccer player is preparing to kick the ball downfield, elaborate on what will result in the maximum distance?
A) The player should kick the ball as hard as possible, the angle doesn't matter. B) The player should increase the ball's initial velocity and kick at a 20° angle. C) The player should increase the ball's initial velocity and kick it at a 30° angle. D) The player should increase the ball's initial velocity and kick it at a 45° angle.
8) A hiker moves 3 meters east, which is vector A. Then the hiker moves four meters north, which is vector B. The displacement vector is vector C. What angle is created between vectors C and A?
A) 37.2°
B) 53.1°
C) 90.5°
D) 100.8°
9) What two factors affect projectile motion?
A) distance and angle
B) distance and amplitude
C) initial velocity and angle
D) initial velocity and amplitude
10) What is the initial upward velocity of a projectile fired at an angle of 40 m/s at an angle of 20o?
A) 2 m/s
B) 13.68 m/s
C) 14.55 m/s
D) 38 m/s
11) At what angle with the ground should a projectile be thrown to reach the maximum distance?
A) 0° with the ground
B) 45° with the ground
C) 62° with the ground
D) 82° with the ground
12) A baseball is hit at an initial speed of 40 m/s at an angle of 60° above the horizontal. Find the ball’s maximum height in meters. Use g = 9.81 m/s2.
A) 10.2
B) 20.4
C) 22.4
D) 61.2
13) Which is an example of two-dimensional motion?
A) a bird flying in the air B) a leaf falling from a tree C) a train traveling along a track D) a lady bug crawling on a soccer ball

Answered by admin @ 28/10/2021

1.)Answer:

The correct answer is C.

Explanation:

Displacement is a vector quantity so it may be either positive or negative. As per convention, acceleration taken as positive when moves downward direction. But, in our case, acceleration towards downward taken as negative, so displacement should also be negative because negative sign only indicate its downward direction.

2.) Answer

The correct answer is C. The time won't change, but horizontal distance will double.

Explanation:

First case

velocity = v = 20 m/s

Height = h = 10 m

We need to calculate time (t) and horizontal distance (x)

using 2nd equation of motion

h = vt + 0.5 gt²

As initial vertical velocity is 0. So

h = 0.5(9.8)t²

It can be see that time does not depends on initial velocity, so it won't change

to calculate x

x = vt

It can be see that horizontal distance will double because depends on velocity.

3.)Question

Illustration:

Day 1: 10 km west and spent night at A.

Day 2: 10 km west and night in a tent B.

Day 3: 20 km west and then they turned around and went back to the home because Jerry left his allergy medicine.

Day 4: 30 km North to the point D.

Answer

The correct answer is C.

Explanation:

On Day 1, Day 2 and Day 3, they move towards west 40 km from home and then turned back to home because Jerry forget his medicine. Thus the total distance is 80 km but the displacement is zero because displacement is the measure from initial to final position. As initial and final position is same at the end of 3rd day so displacement is zero. Fourth day, They move towards north 30 km and hence total distance is 110 km. And total displacement is only 30 km.

4.) Answer:

The correct Answer is A.

Explanation:

To calculate horizontal distance (x), we only need to find the horizontal component of velocity that is

vₓ = v Cos (70°)

vₓ = 41 m/s

As we know that x = vₓ t

So,

x = 41t

5.) Answer

The correct Answer is B.

Explanation:

Displacement is a vector quantity so it depends on direction. As Sally moves 10m forward and then 5m backward, So his total displacement is 5m. While the distance is scalar quantity independent of direction. So the total distance covered by Sally is 15m which is 10m greater than the displacement.

6.)Answer

The correct answer is A.

Explanation:

Consider

horizontal(h)= 6m

vertical = Xm

Hypotenuse(H) = ?

Angle = 37°

As we know that

H×Cos∅ = h

So,

H = h ÷ Cos(∅)

= 6 ÷ Cos(37)

H = 7.5 m

7.) Answer:

The correct answer is D.

Explanation:

In projectile motion, horizontal distance depends on initial velocity and angle with ground. So as the player increase the velocity of the ball, more distance will be covered. As far as he increase the angle upto 45° with the ground, the horizontal distance will increase. That's why the player should increase the ball's initial velocity and kick it at a 45° angle.

8.)Answer:

The correct Answer is B.

Explanation:

Consider

Vector A = 3m

Vector B = 4m

Angle = ?

As the angle ∅ is created between vectors C and A.

we know that

tan∅ = vertical ÷ horizontal

tan∅ = 4 ÷ 3

∅ = tan⁻¹ (1.33)

∅ = 53.1°

9.) Answer:

The correct Answer is C.

Explanation:

Projectile motion depends on initial velocity and initial angle with ground. As far as we increase the velocity of the ball, more distance will be covered. As it also depends on angle, So as far as we increase the angle up to 45° with the ground, the horizontal distance will increase. But when the angle is above 45°, increasing angle decrease the horizontal distance.

10.) Answer:

The correct Answer is B.

Explanation:

Given data :

∅ = 20°

initial velocity = 40 m/s

As we need to find the vertical component of velocity

So, initial upward velocity = initial velocity × Sin∅ = 40 × Sin 20°

initial upward velocity = 13.68 m/s

11.)Answer:

The correct Answer is B.

Explanation:

The projectile motion depends on the angle with the horizontal.As far as we increase the angle up to 45° with the ground, the distance will increase. But when the angle is above 45°, increasing angle decrease the horizontal distance.

12.) Answer:

The correct answer is D.

Explanation:

Given data

Initial speed = V₀ =40 m/s

angle = 60°

g = 9.81 m/s²

First we need to find initial vertical velocity (V)

V = V₀ Sin∅

V = 34.64 m/s

3rd equation of motion

2gh = V₁² - V²

As we need to find maximum height so at highest point vertical final velocity (V₁) = 0

So,

h = V² ÷ 2g

= 34.64² ÷ 2×9.81

h = 61.2 m

13.) Answer:

The correct answer is C.

Explanation:

A bird flying in the air is 3D motion as the bird move up, down, right, left all the possible direction. A leaf falling from a tree is also a 3D motion because a leaf never fall in absolute vertical manner. A lady bug crawling on a soccer ball also 3D. If lady bug crawling on a plane like floor then it is 2D but now lady bug crawling on soccer ball which is in spherical shape so it is also 3D motion. Only train travelling along a track is 2D because train cannot move up and down and the track of train is in a plane. So it is 2D motion.