Question

1. If a particle has negative velocity and negative acceleration, its speed
a) increases b) decreases c) remains same d) zero
2. If an object is dropped from the top of a building and it reaches the ground at t = 4 s,
then the height of the building is (g = 9.8 ms-)
a) 77.3 m b) 78.4 m c) 80.5 m d) 79.2 m
3. A ball is projected vertically upwards with a velocity v. It comes back to ground in
time t. Which v-t graph shows the motion correctly?
(a)
(b)
(c)
(d)
4. If a particle executes uniform circular motion, choose the correct statement
(a) The velocity and speed are constant.
(b) The acceleration and speed are constant
(c) The velocity and acceleration are constant.
(d) The speed and magnitude of acceleration are constant.
please answer my question and and give a correct answer and I will follow you and thank you vote you and rate you and Mark as brainalist...​

Answer 1

1. . If a particle has negative velocity and negative acceleration, its speed increases.

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$\huge\fcolorbox{re}{yelow}{Question}$

If an object is dropped from the top of a building and it reaches the ground at t = 4 s,

then the height of the building is (g = 9.8 ms-).

$\huge\fcolorbox{re}{yelow}{Solution}$

Given,

An object is dropped from a building so the initial velocity is 0. And it reaches ground in 4seconds. The acceleration due to gravity is 9.8m/s². We have to find the height of the building. To find the height of the building we can use the third equation of motion.

u = 0 ; t = 4 sec ; a = 9.8m/s² ; s = ?

➣ s = ut + 1/2 at²

➣ s = 1/2 × 9.8 × 4 × 4

➣ s = 4.9 × 4 × 4

➣ s = 78.4 m

$\boxed{✐ Hence \: the \: height \: of \: the \: building \: is \: 78.4m.}$

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3.

If a particle executes uniform circular motion, choose the correct statement

(a) The velocity and speed are constant.

(b) The acceleration and speed are constant.

(c) The velocity and acceleration are constant.

(d) The speed and magnitude of acceleration are constant.

Solution:-

d. The speed and magnitude of acceleration are constant.

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