A ball is thrown vertically upward from the top of a tower 40m high with velocity 10m/sec find time when it strikes ground

Explanation:

Displacement ⇒ -40 m (the ball strikes the ground)

Initial velocity ⇒ 10 m/s

Acceleration of gravity ⇒ -10 m/s² (upward acceleration)

We can use a formula to find the time taken.

Plugging in the values.

Solve for .

Factor the quadratic expression.

Set the factors equal to 0.

t = -2 and t = 4 (time value will not be negative in this case)

The time the ball takes to strike the ground is 4 seconds.

Find time when it strikes ground.

s = ut + 1/2 at²

We will first calculate the time taken by the ball to reach the highest point by using the formula:

S = ut + 1/2 at²

★ Substituting the values in the above formula,we get:

⇒ -40 = 10 × t + 1/2 × -10 × t²

⇒ -40 = 10t + ( - 5 ) × t²

⇒ -40 = 10t - 5 t²

⇒ 5t² - 10t - 40

⇒ 5t² - 20t + 10t - 40

⇒ 5t ( t - 4 ) + 10 ( t - 4 )

⇒ t - 4 = 0 and 5t + 10 = 0

⇒ t = 4 and t = -2

Thus,time taken is 4 seconds. [ Ignore negative number. ]

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg