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.
