A ForCe of 500 Nacts on a body of mass 1000 kg and body is bought to rest within a distance of 6 um . Find the initial velocity and time taken by the body to come to rest.
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To find the initial velocity, we can use the work-energy principle, where the work done by the force equals the change in kinetic energy. The work done by the force \( F \) over distance \( d \) is given by \( W = F \times d \). Here, \( W = 500 \, \text{N} \times 6 \, \text{m} = 3000 \, \text{J} \). The kinetic energy when the body was in motion was transformed into work done against the force. The change in kinetic energy, which equals the initial kinetic energy (since final kinetic energy is zero upon coming to rest), is given by \( KE = \frac{1}{2}mv^2 \). Setting the work equal to the kinetic energy gives us: \[ 3000 = \frac{1}{2} \times 1000 \times v^2 \] Solving for \( v \): \[ v^2 = \frac{6000}{1000} = 6 \] \[ v = \sqrt{6} \approx 2.45 \, \text{m/s} \] Now, to find the time taken to come to rest, we can use the formula \( F = ma \) to find the deceleration \( a \): \[ a = \frac{F}{m} = \frac{500}{1000} = 0.5 \, \text{m/s}^2 \] Since the body is coming to rest, the acceleration will be negative: \[ a = -0.5 \, \text{m/s}^2 \] Using the formula \( v = u + at \), where \( v = 0 \) m/s, \( u = 2.45 \, \text{m/s} \): \[ 0 = 2.45 - 0.5t \] Solving for \( t \): \[ 0.5t = 2.45 \] \[ t = \frac{2.45}{0.5} \approx 4.9 \, \text{s} \] So the initial velocity is approximately \( 2.45 \, \text{m/s} \) and the time taken to come to rest is about \( 4.9 \, \text{s} \).